diff --git a/backend/app/api/api_v1/endpoints/settings.py b/backend/app/api/api_v1/endpoints/settings.py
index 785b3f5..0872a8a 100644
--- a/backend/app/api/api_v1/endpoints/settings.py
+++ b/backend/app/api/api_v1/endpoints/settings.py
@@ -21,6 +21,7 @@ from sqlalchemy.orm import Session
 from app.core.database import get_db
 from app.core.security import require_admin_auth
 from app.models.setting import Setting
+from app.services.alert_rules import evaluate_alert_rules, send_current_alerts
 from app.services.notifications import send_notification
 
 router = APIRouter()
@@ -127,6 +128,55 @@ SETTING_DEFAULTS: List[Dict[str, Any]] = [
         "value_type": "string",
         "category": "notifications",
     },
+    {
+        "key": "notifications.alert_new_sources_enabled",
+        "value": "true",
+        "description": "Alert when a new sending source appears in recent DMARC reports",
+        "value_type": "boolean",
+        "category": "notifications",
+    },
+    {
+        "key": "notifications.alert_compliance_drop_enabled",
+        "value": "true",
+        "description": "Alert when DMARC compliance drops by the configured percentage points",
+        "value_type": "boolean",
+        "category": "notifications",
+    },
+    {
+        "key": "notifications.alert_compliance_drop_points",
+        "value": "10",
+        "description": "Minimum compliance-rate drop, in percentage points, before alerting",
+        "value_type": "integer",
+        "category": "notifications",
+    },
+    {
+        "key": "notifications.alert_failure_threshold_enabled",
+        "value": "true",
+        "description": "Alert when DMARC failures exceed the configured daily threshold",
+        "value_type": "boolean",
+        "category": "notifications",
+    },
+    {
+        "key": "notifications.alert_failure_threshold_count",
+        "value": "100",
+        "description": "Minimum failed message count in the last day before alerting",
+        "value_type": "integer",
+        "category": "notifications",
+    },
+    {
+        "key": "notifications.alert_missing_reports_enabled",
+        "value": "true",
+        "description": "Alert when a monitored domain has not received recent DMARC reports",
+        "value_type": "boolean",
+        "category": "notifications",
+    },
+    {
+        "key": "notifications.alert_missing_reports_days",
+        "value": "2",
+        "description": "Number of days without DMARC reports before alerting",
+        "value_type": "integer",
+        "category": "notifications",
+    },
 ]
 
 # Keys whose values should be redacted in GET responses (treated as secrets)
@@ -216,6 +266,19 @@ class NotificationTestResponse(BaseModel):
     error: Optional[str] = None
 
 
+class AlertRulesResponse(BaseModel):
+    """Current alert-rule evaluation response."""
+
+    alerts: List[Dict[str, Any]]
+
+
+class AlertNotificationResponse(BaseModel):
+    """Alert-rule evaluation plus notification delivery status."""
+
+    alerts: List[Dict[str, Any]]
+    notification: Dict[str, Any]
+
+
 # ---------------------------------------------------------------------------
 # Endpoints
 # ---------------------------------------------------------------------------
@@ -261,6 +324,33 @@ async def test_notification_settings(
     return result.to_dict()
 
 
+@router.get("/notifications/alerts", response_model=AlertRulesResponse)
+async def evaluate_notification_alerts(
+    db: Session = Depends(get_db),
+    _auth: dict = Depends(require_admin_auth),
+) -> AlertRulesResponse:
+    """Evaluate enabled notification alert rules against current DMARC data."""
+    _seed_defaults(db)
+    return {"alerts": evaluate_alert_rules(db)}
+
+
+@router.post("/notifications/alerts/send", response_model=AlertNotificationResponse)
+async def send_notification_alerts(
+    db: Session = Depends(get_db),
+    _auth: dict = Depends(require_admin_auth),
+) -> AlertNotificationResponse:
+    """Evaluate current alert rules and send a notification summary when needed."""
+    _seed_defaults(db)
+    result = send_current_alerts(db)
+    notification = result["notification"]
+    if result["alerts"] and not notification.get("success"):
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail=result,
+        )
+    return result
+
+
 @router.get("/{key:path}", response_model=SettingResponse)
 async def get_setting(
     key: str,
diff --git a/backend/app/services/alert_rules.py b/backend/app/services/alert_rules.py
new file mode 100644
index 0000000..829f969
--- /dev/null
+++ b/backend/app/services/alert_rules.py
@@ -0,0 +1,256 @@
+"""Alert rule evaluation for DMARC report data."""
+
+from __future__ import annotations
+
+from datetime import datetime, timedelta, timezone
+from typing import Any, Dict, List, Optional
+
+from sqlalchemy import case, func
+from sqlalchemy.orm import Session
+
+from app.models.domain import Domain
+from app.models.report import DMARCReport, ReportRecord
+from app.models.setting import Setting
+from app.services.notifications import NotificationResult, send_notification
+
+
+def _truthy(value: Optional[str], default: bool = True) -> bool:
+    if value in (None, ""):
+        return default
+    return str(value).strip().lower() in {"1", "true", "yes", "on"}
+
+
+def _int_setting(value: Optional[str], default: int) -> int:
+    try:
+        return int(value or default)
+    except (TypeError, ValueError):
+        return default
+
+
+def _settings(db: Session) -> Dict[str, Optional[str]]:
+    rows = db.query(Setting).filter(Setting.category == "notifications").all()
+    return {row.key: row.value for row in rows}
+
+
+def _days_ago_ts(days: int) -> int:
+    return int((datetime.now(timezone.utc) - timedelta(days=days)).timestamp())
+
+
+def _new_source_alerts(db: Session, window_days: int = 7) -> List[Dict[str, Any]]:
+    cutoff_ts = _days_ago_ts(window_days)
+    previous_sources = {
+        (row.domain, row.source_ip)
+        for row in (
+            db.query(Domain.name.label("domain"), ReportRecord.source_ip.label("source_ip"))
+            .join(DMARCReport, DMARCReport.domain_id == Domain.id)
+            .join(ReportRecord, ReportRecord.report_id == DMARCReport.id)
+            .filter(DMARCReport.begin_date < cutoff_ts)
+            .distinct()
+            .all()
+        )
+    }
+
+    current_sources = (
+        db.query(
+            Domain.name.label("domain"),
+            ReportRecord.source_ip.label("source_ip"),
+            func.sum(ReportRecord.count).label("message_count"),
+        )
+        .join(DMARCReport, DMARCReport.domain_id == Domain.id)
+        .join(ReportRecord, ReportRecord.report_id == DMARCReport.id)
+        .filter(DMARCReport.begin_date >= cutoff_ts)
+        .group_by(Domain.name, ReportRecord.source_ip)
+        .order_by(func.sum(ReportRecord.count).desc())
+        .all()
+    )
+
+    alerts = []
+    for row in current_sources:
+        if (row.domain, row.source_ip) in previous_sources:
+            continue
+        count = int(row.message_count or 0)
+        alerts.append(
+            {
+                "rule": "new_sender_source",
+                "severity": "warning",
+                "domain": row.domain,
+                "source_ip": row.source_ip,
+                "message_count": count,
+                "title": "New sending source",
+                "detail": f"{row.source_ip} first appeared for {row.domain} with {count} messages.",
+            }
+        )
+    return alerts
+
+
+def _failure_threshold_alerts(
+    db: Session, threshold: int, window_days: int = 1
+) -> List[Dict[str, Any]]:
+    cutoff_ts = _days_ago_ts(window_days)
+    rows = (
+        db.query(
+            Domain.name.label("domain"),
+            func.sum(ReportRecord.count).label("failed_messages"),
+        )
+        .join(DMARCReport, DMARCReport.domain_id == Domain.id)
+        .join(ReportRecord, ReportRecord.report_id == DMARCReport.id)
+        .filter(DMARCReport.begin_date >= cutoff_ts)
+        .filter(func.coalesce(ReportRecord.dkim, "fail") != "pass")
+        .filter(func.coalesce(ReportRecord.spf, "fail") != "pass")
+        .group_by(Domain.name)
+        .having(func.sum(ReportRecord.count) >= threshold)
+        .all()
+    )
+    return [
+        {
+            "rule": "dmarc_failures_above_threshold",
+            "severity": "error",
+            "domain": row.domain,
+            "failed_messages": int(row.failed_messages or 0),
+            "threshold": threshold,
+            "title": "DMARC failures above threshold",
+            "detail": (
+                f"{row.domain} had {int(row.failed_messages or 0)} DMARC failures "
+                f"in the last {window_days} day(s)."
+            ),
+        }
+        for row in rows
+    ]
+
+
+def _missing_report_alerts(db: Session, missing_days: int) -> List[Dict[str, Any]]:
+    cutoff_ts = _days_ago_ts(missing_days)
+    latest_rows = (
+        db.query(
+            Domain.name.label("domain"),
+            func.max(DMARCReport.end_date).label("last_report_ts"),
+        )
+        .outerjoin(DMARCReport, DMARCReport.domain_id == Domain.id)
+        .group_by(Domain.id, Domain.name)
+        .all()
+    )
+    alerts = []
+    for row in latest_rows:
+        last_report_ts = int(row.last_report_ts or 0)
+        if last_report_ts >= cutoff_ts:
+            continue
+        alerts.append(
+            {
+                "rule": "missing_reports",
+                "severity": "warning",
+                "domain": row.domain,
+                "missing_days": missing_days,
+                "last_report_at": (
+                    datetime.fromtimestamp(last_report_ts, tz=timezone.utc).isoformat()
+                    if last_report_ts
+                    else None
+                ),
+                "title": "Missing DMARC reports",
+                "detail": f"{row.domain} has no DMARC report in the last {missing_days} day(s).",
+            }
+        )
+    return alerts
+
+
+def _compliance_drop_alerts(
+    db: Session, drop_points: int, window_days: int = 2
+) -> List[Dict[str, Any]]:
+    cutoff_ts = _days_ago_ts(window_days)
+    rows = (
+        db.query(
+            Domain.name.label("domain"),
+            DMARCReport.begin_date.label("begin_date"),
+            func.sum(ReportRecord.count).label("total"),
+            func.sum(
+                case(
+                    (
+                        (ReportRecord.dkim == "pass") | (ReportRecord.spf == "pass"),
+                        ReportRecord.count,
+                    ),
+                    else_=0,
+                )
+            ).label("passed"),
+        )
+        .join(DMARCReport, DMARCReport.domain_id == Domain.id)
+        .join(ReportRecord, ReportRecord.report_id == DMARCReport.id)
+        .filter(DMARCReport.begin_date >= cutoff_ts)
+        .group_by(Domain.name, DMARCReport.begin_date)
+        .order_by(Domain.name, DMARCReport.begin_date)
+        .all()
+    )
+
+    by_domain: Dict[str, List[Dict[str, float]]] = {}
+    for row in rows:
+        total = int(row.total or 0)
+        passed = int(row.passed or 0)
+        rate = round((passed / total) * 100, 1) if total else 0.0
+        by_domain.setdefault(row.domain, []).append({"date": row.begin_date, "rate": rate})
+
+    alerts = []
+    for domain, points in by_domain.items():
+        if len(points) < 2:
+            continue
+        previous = points[-2]
+        current = points[-1]
+        drop = round(previous["rate"] - current["rate"], 1)
+        if drop < drop_points:
+            continue
+        alerts.append(
+            {
+                "rule": "compliance_drop",
+                "severity": "error" if drop >= 25 else "warning",
+                "domain": domain,
+                "previous_rate": previous["rate"],
+                "current_rate": current["rate"],
+                "drop": drop,
+                "threshold": drop_points,
+                "title": "Compliance dropped",
+                "detail": f"{domain} compliance fell by {drop} percentage points.",
+            }
+        )
+    return alerts
+
+
+def evaluate_alert_rules(db: Session) -> List[Dict[str, Any]]:
+    """Evaluate all enabled alert rules against persisted DMARC data."""
+    settings = _settings(db)
+    alerts: List[Dict[str, Any]] = []
+
+    if _truthy(settings.get("notifications.alert_new_sources_enabled")):
+        alerts.extend(_new_source_alerts(db))
+
+    if _truthy(settings.get("notifications.alert_failure_threshold_enabled")):
+        threshold = _int_setting(settings.get("notifications.alert_failure_threshold_count"), 100)
+        alerts.extend(_failure_threshold_alerts(db, threshold))
+
+    if _truthy(settings.get("notifications.alert_missing_reports_enabled")):
+        missing_days = _int_setting(settings.get("notifications.alert_missing_reports_days"), 2)
+        alerts.extend(_missing_report_alerts(db, missing_days))
+
+    if _truthy(settings.get("notifications.alert_compliance_drop_enabled")):
+        drop_points = _int_setting(settings.get("notifications.alert_compliance_drop_points"), 10)
+        alerts.extend(_compliance_drop_alerts(db, drop_points))
+
+    return alerts
+
+
+def send_current_alerts(db: Session) -> Dict[str, Any]:
+    """Evaluate current alert rules and send one summary notification when needed."""
+    alerts = evaluate_alert_rules(db)
+    if not alerts:
+        return {
+            "alerts": [],
+            "notification": NotificationResult(
+                success=True, skipped=True, message="No alerts."
+            ).to_dict(),
+        }
+
+    lines = [f"{alert['title']}: {alert['detail']}" for alert in alerts[:10]]
+    if len(alerts) > 10:
+        lines.append(f"...and {len(alerts) - 10} more alert(s).")
+    result = send_notification(
+        db,
+        title=f"DMARQ alert summary: {len(alerts)} alert(s)",
+        body="\n".join(lines),
+    )
+    return {"alerts": alerts, "notification": result.to_dict()}
diff --git a/backend/app/templates/settings.html b/backend/app/templates/settings.html
index 2b3e1f8..eeea592 100644
--- a/backend/app/templates/settings.html
+++ b/backend/app/templates/settings.html
@@ -235,7 +235,100 @@
                     </div>
                 </template>
 
+                <div class="border-t border-border pt-4 space-y-4">
+                    <div>
+                        <h3 class="text-sm font-semibold">Alert Rules</h3>
+                    </div>
+
+                    <div class="grid grid-cols-1 md:grid-cols-2 gap-4">
+                        <div class="form-control">
+                            <label class="label cursor-pointer justify-start gap-3">
+                                <input type="checkbox"
+                                    :checked="s['notifications.alert_new_sources_enabled'] === 'true'"
+                                    @change="s['notifications.alert_new_sources_enabled'] = $event.target.checked ? 'true' : 'false'"
+                                    class="checkbox checkbox-primary" />
+                                <span class="label-text font-medium">New sending sources</span>
+                            </label>
+                        </div>
+
+                        <div class="form-control">
+                            <label class="label cursor-pointer justify-start gap-3">
+                                <input type="checkbox"
+                                    :checked="s['notifications.alert_missing_reports_enabled'] === 'true'"
+                                    @change="s['notifications.alert_missing_reports_enabled'] = $event.target.checked ? 'true' : 'false'"
+                                    class="checkbox checkbox-primary" />
+                                <span class="label-text font-medium">Missing reports</span>
+                            </label>
+                        </div>
+
+                        <div class="form-control">
+                            <label class="label cursor-pointer justify-start gap-3">
+                                <input type="checkbox"
+                                    :checked="s['notifications.alert_failure_threshold_enabled'] === 'true'"
+                                    @change="s['notifications.alert_failure_threshold_enabled'] = $event.target.checked ? 'true' : 'false'"
+                                    class="checkbox checkbox-primary" />
+                                <span class="label-text font-medium">High DMARC failures</span>
+                            </label>
+                        </div>
+
+                        <div class="form-control">
+                            <label class="label cursor-pointer justify-start gap-3">
+                                <input type="checkbox"
+                                    :checked="s['notifications.alert_compliance_drop_enabled'] === 'true'"
+                                    @change="s['notifications.alert_compliance_drop_enabled'] = $event.target.checked ? 'true' : 'false'"
+                                    class="checkbox checkbox-primary" />
+                                <span class="label-text font-medium">Compliance drops</span>
+                            </label>
+                        </div>
+                    </div>
+
+                    <div class="grid grid-cols-1 md:grid-cols-3 gap-4">
+                        <div class="form-control w-full">
+                            <label class="label"><span class="label-text font-medium">Failure Threshold</span></label>
+                            <input type="number" x-model.number="s['notifications.alert_failure_threshold_count']"
+                                class="input input-bordered w-full" min="1" />
+                        </div>
+                        <div class="form-control w-full">
+                            <label class="label"><span class="label-text font-medium">Missing After Days</span></label>
+                            <input type="number" x-model.number="s['notifications.alert_missing_reports_days']"
+                                class="input input-bordered w-full" min="1" />
+                        </div>
+                        <div class="form-control w-full">
+                            <label class="label"><span class="label-text font-medium">Drop Points</span></label>
+                            <input type="number" x-model.number="s['notifications.alert_compliance_drop_points']"
+                                class="input input-bordered w-full" min="1" max="100" />
+                        </div>
+                    </div>
+
+                    <template x-if="alertPreview !== null">
+                        <div class="alert" :class="alertPreview > 0 ? 'alert-warning' : 'alert-success'">
+                            <span x-text="alertPreview > 0 ? `${alertPreview} active alert${alertPreview === 1 ? '' : 's'} found.` : 'No active alerts found.'"></span>
+                        </div>
+                    </template>
+                </div>
+
                 <div class="flex flex-col sm:flex-row justify-end gap-2">
+                    <button type="button" class="btn btn-outline btn-md" :disabled="saving || checkingAlerts" @click="checkAlerts()">
+                        <template x-if="!checkingAlerts">
+                            <svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none"
+                                stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="mr-2">
+                                <path d="M22 12h-4l-3 9L9 3l-3 9H2"></path>
+                            </svg>
+                        </template>
+                        <template x-if="checkingAlerts"><span class="loading loading-spinner loading-xs mr-2"></span></template>
+                        Check Alerts
+                    </button>
+                    <button type="button" class="btn btn-outline btn-md" :disabled="saving || sendingAlerts" @click="sendAlertSummary()">
+                        <template x-if="!sendingAlerts">
+                            <svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none"
+                                stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="mr-2">
+                                <path d="M10.268 21a2 2 0 0 0 3.464 0"></path>
+                                <path d="M3.262 15.326A1 1 0 0 0 4 17h16a1 1 0 0 0 .74-1.673C19.41 13.956 18 12.499 18 8A6 6 0 0 0 6 8c0 4.499-1.411 5.956-2.738 7.326"></path>
+                            </svg>
+                        </template>
+                        <template x-if="sendingAlerts"><span class="loading loading-spinner loading-xs mr-2"></span></template>
+                        Send Alerts Now
+                    </button>
                     <button type="button" class="btn btn-outline btn-md" :disabled="saving || testingNotification" @click="sendTestNotification()">
                         <template x-if="!testingNotification">
                             <svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none"
@@ -292,6 +385,9 @@ function settingsApp() {
         flashMsg: '',
         flashOk: true,
         testingNotification: false,
+        checkingAlerts: false,
+        sendingAlerts: false,
+        alertPreview: null,
         showCfToken: false,
 
         // Session cookie is sent automatically by the browser (httpOnly, same-origin).
@@ -369,6 +465,51 @@ function settingsApp() {
             }
         },
 
+        async checkAlerts() {
+            this.checkingAlerts = true;
+            try {
+                await this.saveCategory('notifications');
+                const res = await fetch('/api/v1/settings/notifications/alerts', {
+                    headers: this.apiHeaders(),
+                });
+                const data = await res.json().catch(() => ({}));
+                if (!res.ok) {
+                    this.showFlash('Alert check failed: ' + (data.detail || res.statusText), false);
+                } else {
+                    this.alertPreview = (data.alerts || []).length;
+                    this.showFlash(`${this.alertPreview} active alert${this.alertPreview === 1 ? '' : 's'} found.`, true);
+                }
+            } catch (err) {
+                this.showFlash('Error checking alerts: ' + err.message, false);
+            } finally {
+                this.checkingAlerts = false;
+            }
+        },
+
+        async sendAlertSummary() {
+            this.sendingAlerts = true;
+            try {
+                await this.saveCategory('notifications');
+                const res = await fetch('/api/v1/settings/notifications/alerts/send', {
+                    method: 'POST',
+                    headers: this.apiHeaders(),
+                });
+                const data = await res.json().catch(() => ({}));
+                if (!res.ok) {
+                    const detail = data.detail || {};
+                    const notification = detail.notification || {};
+                    this.showFlash('Alert send failed: ' + (notification.message || data.detail || res.statusText), false);
+                } else {
+                    this.alertPreview = (data.alerts || []).length;
+                    this.showFlash(data.notification.skipped ? 'No active alerts to send.' : 'Alert summary sent.', true);
+                }
+            } catch (err) {
+                this.showFlash('Error sending alerts: ' + err.message, false);
+            } finally {
+                this.sendingAlerts = false;
+            }
+        },
+
         showFlash(msg, ok) {
             this.flashMsg = msg;
             this.flashOk = ok;
diff --git a/backend/app/tests/test_settings.py b/backend/app/tests/test_settings.py
index 892bc8d..d6a3e1c 100644
--- a/backend/app/tests/test_settings.py
+++ b/backend/app/tests/test_settings.py
@@ -2,10 +2,61 @@
 Tests for the Settings model and /api/v1/settings endpoints.
 """
 
+from datetime import datetime, timedelta, timezone
+
 from fastapi.testclient import TestClient
 from sqlalchemy.orm import Session
 
+from app.models.domain import Domain
+from app.models.report import DMARCReport, ReportRecord
 from app.models.setting import Setting
+from app.services.notifications import NotificationResult
+
+
+def _timestamp_days_ago(days: int) -> int:
+    return int((datetime.now(timezone.utc) - timedelta(days=days)).timestamp())
+
+
+def _add_domain(db_session: Session, name: str) -> Domain:
+    domain = Domain(name=name)
+    db_session.add(domain)
+    db_session.flush()
+    return domain
+
+
+def _add_report_record(
+    db_session: Session,
+    domain: Domain,
+    *,
+    report_id: str,
+    days_ago: int,
+    source_ip: str,
+    count: int,
+    dkim: str = "pass",
+    spf: str = "pass",
+) -> None:
+    begin_date = _timestamp_days_ago(days_ago)
+    report = DMARCReport(
+        domain_id=domain.id,
+        report_id=report_id,
+        org_name="receiver.example",
+        begin_date=begin_date,
+        end_date=begin_date + 3600,
+        policy="none",
+    )
+    db_session.add(report)
+    db_session.flush()
+    db_session.add(
+        ReportRecord(
+            report_id=report.id,
+            source_ip=source_ip,
+            count=count,
+            disposition="none",
+            dkim=dkim,
+            spf=spf,
+            header_from=domain.name,
+        )
+    )
 
 
 class TestSettingModel:
@@ -51,6 +102,10 @@ class TestSettingsAPI:
         assert "cloudflare.api_token" in keys
         assert "notifications.apprise_enabled" in keys
         assert "notifications.apprise_urls" in keys
+        assert "notifications.alert_new_sources_enabled" in keys
+        assert "notifications.alert_compliance_drop_points" in keys
+        assert "notifications.alert_failure_threshold_count" in keys
+        assert "notifications.alert_missing_reports_days" in keys
 
     def test_list_settings_filter_by_category(self, authed_client: TestClient):
         """GET /api/v1/settings?category=dmarc returns only dmarc settings."""
@@ -213,3 +268,145 @@ class TestSettingsAPI:
         detail = res.json()["detail"]
         assert detail["success"] is False
         assert detail["message"] == "No notification targets are configured."
+
+    def test_notification_alert_rules_detect_new_source_and_failures(
+        self,
+        authed_client: TestClient,
+        db_session: Session,
+    ):
+        """GET /settings/notifications/alerts evaluates source and failure alerts."""
+        domain = _add_domain(db_session, "alerts.example")
+        _add_report_record(
+            db_session,
+            domain,
+            report_id="alerts-old-source",
+            days_ago=10,
+            source_ip="203.0.113.10",
+            count=12,
+        )
+        _add_report_record(
+            db_session,
+            domain,
+            report_id="alerts-new-source",
+            days_ago=0,
+            source_ip="203.0.113.20",
+            count=150,
+            dkim="fail",
+            spf="fail",
+        )
+        db_session.commit()
+
+        res = authed_client.get("/api/v1/settings/notifications/alerts")
+
+        assert res.status_code == 200
+        alerts = res.json()["alerts"]
+        rules = {alert["rule"] for alert in alerts}
+        assert "new_sender_source" in rules
+        assert "dmarc_failures_above_threshold" in rules
+        new_source = next(alert for alert in alerts if alert["rule"] == "new_sender_source")
+        assert new_source["source_ip"] == "203.0.113.20"
+
+    def test_notification_alert_rules_detect_missing_reports(
+        self,
+        authed_client: TestClient,
+        db_session: Session,
+    ):
+        """Alert rules flag active monitored domains without recent reports."""
+        _add_domain(db_session, "missing.example")
+        db_session.commit()
+
+        res = authed_client.get("/api/v1/settings/notifications/alerts")
+
+        assert res.status_code == 200
+        alerts = res.json()["alerts"]
+        assert any(
+            alert["rule"] == "missing_reports" and alert["domain"] == "missing.example"
+            for alert in alerts
+        )
+
+    def test_notification_alert_rules_detect_compliance_drop(
+        self,
+        authed_client: TestClient,
+        db_session: Session,
+    ):
+        """Alert rules compare recent compliance rates and flag large drops."""
+        domain = _add_domain(db_session, "drop.example")
+        _add_report_record(
+            db_session,
+            domain,
+            report_id="drop-known-source",
+            days_ago=10,
+            source_ip="203.0.113.30",
+            count=3,
+        )
+        _add_report_record(
+            db_session,
+            domain,
+            report_id="drop-passing-day",
+            days_ago=1,
+            source_ip="203.0.113.30",
+            count=10,
+        )
+        _add_report_record(
+            db_session,
+            domain,
+            report_id="drop-failing-day",
+            days_ago=0,
+            source_ip="203.0.113.30",
+            count=10,
+            dkim="fail",
+            spf="fail",
+        )
+        db_session.commit()
+
+        res = authed_client.get("/api/v1/settings/notifications/alerts")
+
+        assert res.status_code == 200
+        alerts = res.json()["alerts"]
+        compliance_alert = next(alert for alert in alerts if alert["rule"] == "compliance_drop")
+        assert compliance_alert["domain"] == "drop.example"
+        assert compliance_alert["previous_rate"] == 100.0
+        assert compliance_alert["current_rate"] == 0.0
+
+    def test_notification_alert_send_uses_alert_summary(
+        self,
+        authed_client: TestClient,
+        db_session: Session,
+        monkeypatch,
+    ):
+        """POST /settings/notifications/alerts/send sends one alert summary."""
+        sent_messages = []
+
+        def fake_send_notification(
+            db, *, title, body, force=False
+        ):  # pylint: disable=unused-argument
+            sent_messages.append({"title": title, "body": body})
+            return NotificationResult(
+                success=True,
+                message="Notification sent.",
+                configured_targets=1,
+            )
+
+        monkeypatch.setattr("app.services.alert_rules.send_notification", fake_send_notification)
+
+        domain = _add_domain(db_session, "send.example")
+        _add_report_record(
+            db_session,
+            domain,
+            report_id="send-failing-day",
+            days_ago=0,
+            source_ip="203.0.113.40",
+            count=200,
+            dkim="fail",
+            spf="fail",
+        )
+        db_session.commit()
+
+        res = authed_client.post("/api/v1/settings/notifications/alerts/send")
+
+        assert res.status_code == 200
+        data = res.json()
+        assert data["notification"]["success"] is True
+        assert data["alerts"]
+        assert sent_messages[0]["title"].startswith("DMARQ alert summary")
+        assert "DMARC failures above threshold" in sent_messages[0]["body"]
diff --git a/docs/deployment/configuration.md b/docs/deployment/configuration.md
index 5a30c7c..bb3b6c3 100644
--- a/docs/deployment/configuration.md
+++ b/docs/deployment/configuration.md
@@ -85,6 +85,13 @@ from API responses.
 |---------|-------------|---------|---------|
 | `notifications.apprise_enabled` | Enable Apprise notification delivery | `false` | `true` |
 | `notifications.apprise_urls` | Newline-separated Apprise target URLs | - | `mailto://user:pass@example.com` |
+| `notifications.alert_new_sources_enabled` | Alert on newly observed sending sources | `true` | `true` |
+| `notifications.alert_compliance_drop_enabled` | Alert on recent compliance-rate drops | `true` | `true` |
+| `notifications.alert_compliance_drop_points` | Minimum compliance-rate drop in percentage points | `10` | `15` |
+| `notifications.alert_failure_threshold_enabled` | Alert on high recent DMARC failure volume | `true` | `true` |
+| `notifications.alert_failure_threshold_count` | Failed messages in the last day before alerting | `100` | `250` |
+| `notifications.alert_missing_reports_enabled` | Alert when a monitored domain stops receiving reports | `true` | `true` |
+| `notifications.alert_missing_reports_days` | Days without reports before alerting | `2` | `3` |
 
 ### Cloudflare Integration
 
diff --git a/docs/development/roadmap.md b/docs/development/roadmap.md
index 722264c..8ae726d 100644
--- a/docs/development/roadmap.md
+++ b/docs/development/roadmap.md
@@ -83,7 +83,7 @@ Follow-up:
 
 ## Later Milestones
 
-- Notifications and alert rules. Apprise delivery and test notifications are in place; alert rules, summaries, and alert history remain.
+- Notifications and alert rules. Apprise delivery, test notifications, and current alert-rule evaluation are in place; scheduled summaries and alert history remain.
 - DNS health and Cloudflare read-only inspection.
 - Guided setup and operator health screens.
 - Forensic/RUF report support.
diff --git a/docs/milestones.md b/docs/milestones.md
index 54e9f79..9e18a63 100644
--- a/docs/milestones.md
+++ b/docs/milestones.md
@@ -114,9 +114,10 @@ Goal: notify administrators when action is needed.
 Delivered:
 - Apprise notification integration for newline-separated notification target URLs.
 - Notification settings UI can save Apprise targets, keeps target URLs redacted after save, and can send a test notification.
+- Alert rules for new sender source, compliance drop, DMARC failures above threshold, and missing reports.
+- Notification settings UI can evaluate active alerts and send the current alert summary on demand.
 
 Planned:
-- Alert rules for new sender source, compliance drop, DMARC failures above threshold, and missing reports.
 - Daily/weekly summary notifications.
 - Alert history.
 
diff --git a/docs/todo.md b/docs/todo.md
index 6591ff4..cdca81d 100644
--- a/docs/todo.md
+++ b/docs/todo.md
@@ -165,7 +165,7 @@ Status: Complete for the delivered reporting milestone. Alert-specific dashboard
 - [x] Add backup/restore guidance for database deployments
 - [x] Add release checklist covering migrations, tests, and smoke checks
 - [x] Add Apprise notification delivery and test notification support
-- [ ] Add alert rules for new sender source, compliance drop, DMARC failures above threshold, and missing reports
+- [x] Add alert rules for new sender source, compliance drop, DMARC failures above threshold, and missing reports
 - [ ] Add daily and weekly summary notifications
 - [ ] Add alert history
 - [ ] DNS health guidance and Cloudflare read-only inspection
diff --git a/docs/user_guide/settings.md b/docs/user_guide/settings.md
index 37e7727..24eaa9c 100644
--- a/docs/user_guide/settings.md
+++ b/docs/user_guide/settings.md
@@ -44,14 +44,15 @@ settings API or page reloads.
 
 ### Alert Thresholds
 
-Set thresholds for when alerts are triggered:
+Set alert rules and thresholds in **Settings** > **Notifications**:
 
-1. Navigate to **Settings** > **Notifications** > **Thresholds**
-2. Configure thresholds for:
-   - **Compliance Rate Drop**: Alert when compliance falls below a threshold
-   - **New Sending Sources**: Alert when new IPs/servers send email as your domain
-   - **Authentication Failures**: Alert when failures exceed a certain number
-   - **Report Processing Issues**: Alert on report processing errors
+- **New Sending Sources**: newly observed IPs or servers sending as a monitored domain
+- **Compliance Drops**: recent compliance-rate drops beyond the configured point threshold
+- **High DMARC Failures**: failed messages over the daily threshold
+- **Missing Reports**: monitored domains without reports for the configured number of days
+
+Use **Check Alerts** to preview the current alert count, or **Send Alerts Now** to
+send the current alert summary through the configured Apprise targets.
 
 ### Integration Notifications