diff --git a/src/models/feedback/Feedback.router.ts b/src/models/feedback/Feedback.router.ts
index 217cca4..655f31b 100644
--- a/src/models/feedback/Feedback.router.ts
+++ b/src/models/feedback/Feedback.router.ts
@@ -2,10 +2,9 @@
  * Required External Modules and Interfaces
  */
 import express, {Request, Response} from 'express';
-import {Guid} from 'guid-typescript';
-import logger from '../../middleware/logger';
 import {publicRouter} from './public/public.router';
 import {adminRouter} from './admin/admin.router';
+import {sendServerError} from './feedback.errors';
 
 /**
  * Router Definition
@@ -52,12 +51,6 @@ feedbackRouter.get('/', async (req: Request, res: Response) => {
 	try {
 		res.status(200).send('Nachklang e.V. Feedback API Endpoint');
 	} catch (e: any) {
-		let errorGuid = Guid.create().toString();
-		logger.error('Error handling a request: ' + e.message, {reference: errorGuid});
-		res.status(500).send({
-			'status': 'PROCESSING_ERROR',
-			'message': 'Internal Server Error. Try again later.',
-			'reference': errorGuid
-		});
+		sendServerError(res, e);
 	}
 });
diff --git a/src/models/feedback/admin/admin.router.ts b/src/models/feedback/admin/admin.router.ts
index abf2a08..e84b410 100644
--- a/src/models/feedback/admin/admin.router.ts
+++ b/src/models/feedback/admin/admin.router.ts
@@ -2,9 +2,8 @@
  * Required External Modules and Interfaces
  */
 import express, {Request, Response} from 'express';
-import {Guid} from 'guid-typescript';
-import logger from '../../../middleware/logger';
 import {requireAdminAuth} from '../feedback.auth';
+import {sendServerError} from '../feedback.errors';
 import {eventsAdminRouter} from './events.admin.router';
 import {songsAdminRouter} from './songs.admin.router';
 import {questionsAdminRouter} from './questions.admin.router';
@@ -81,13 +80,7 @@ adminRouter.delete('/submissions/:submissionId', async (req: Request, res: Respo
 		}
 		res.status(204).send();
 	} catch (e: any) {
-		let errorGuid = Guid.create().toString();
-		logger.error('Error handling a request: ' + e.message, {reference: errorGuid});
-		res.status(500).send({
-			status: 'PROCESSING_ERROR',
-			message: 'Internal Server Error. Try again later.',
-			reference: errorGuid
-		});
+		sendServerError(res, e);
 	}
 });
 
diff --git a/src/models/feedback/admin/csv.service.ts b/src/models/feedback/admin/csv.service.ts
index 0aa91f1..e7f899b 100644
--- a/src/models/feedback/admin/csv.service.ts
+++ b/src/models/feedback/admin/csv.service.ts
@@ -1,4 +1,5 @@
 import {NachklangFeedbackDB} from '../Feedback.db';
+import {formatDatetime} from '../feedback.dates';
 
 const CSV_SEPARATOR = ';';
 const UTF8_BOM = '';
@@ -23,15 +24,6 @@ export const escapeCsvField = (value: string | number | null | undefined): strin
 	return str;
 };
 
-/** mariadb returns DATETIME columns as JS Date objects - format explicitly,
- * otherwise String(date) falls back to the verbose Date.toString() format. */
-export const formatDatetime = (value: Date | string | null): string => {
-	if (!value) return '';
-	const d = value instanceof Date ? value : new Date(value);
-	const pad = (n: number) => String(n).padStart(2, '0');
-	return `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())} ${pad(d.getHours())}:${pad(d.getMinutes())}:${pad(d.getSeconds())}`;
-};
-
 const buildCsv = (headers: string[], rows: (string | number | null | undefined)[][]): string => {
 	const lines = [headers.map(escapeCsvField).join(CSV_SEPARATOR)];
 	for (const row of rows) {
diff --git a/src/models/feedback/admin/events.admin.router.ts b/src/models/feedback/admin/events.admin.router.ts
index e6c075e..8bcaced 100644
--- a/src/models/feedback/admin/events.admin.router.ts
+++ b/src/models/feedback/admin/events.admin.router.ts
@@ -2,26 +2,15 @@
  * Required External Modules and Interfaces
  */
 import express, {Request, Response} from 'express';
-import {Guid} from 'guid-typescript';
-import logger from '../../../middleware/logger';
 import * as EventsAdminService from './events.admin.service';
 import * as SongsAdminService from './songs.admin.service';
+import {sendServerError} from '../feedback.errors';
 
 /**
  * Router Definition
  */
 export const eventsAdminRouter = express.Router();
 
-const sendServerError = (res: Response, e: any) => {
-	let errorGuid = Guid.create().toString();
-	logger.error('Error handling a request: ' + e.message, {reference: errorGuid});
-	res.status(500).send({
-		'status': 'PROCESSING_ERROR',
-		'message': 'Internal Server Error. Try again later.',
-		'reference': errorGuid
-	});
-};
-
 /**
  * @swagger
  * /feedback/admin/events:
diff --git a/src/models/feedback/admin/events.admin.service.ts b/src/models/feedback/admin/events.admin.service.ts
index 03a137d..70075b2 100644
--- a/src/models/feedback/admin/events.admin.service.ts
+++ b/src/models/feedback/admin/events.admin.service.ts
@@ -1,6 +1,7 @@
 import {NachklangFeedbackDB} from '../Feedback.db';
 import {Song} from '../feedback.interface';
 import {CreateEventInput, EventAdminDetail, EventAdminQuestionAssignment, EventAdminSummary, UpdateEventInput} from './admin.interface';
+import {formatDatetime} from '../feedback.dates';
 
 const UMLAUT_MAP: Record<string, string> = {
 	'ä': 'ae', 'ö': 'oe', 'ü': 'ue', 'ß': 'ss',
@@ -83,11 +84,6 @@ const generateUniqueSlug = async (conn: any, name: string, eventDate: string): P
 	}
 };
 
-const toMysqlDatetime = (d: Date): string => {
-	const pad = (n: number) => String(n).padStart(2, '0');
-	return `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())} ${pad(d.getHours())}:${pad(d.getMinutes())}:${pad(d.getSeconds())}`;
-};
-
 export const createEvent = async (input: CreateEventInput, createdByEmail: string): Promise<number> => {
 	let conn = await NachklangFeedbackDB.getConnection();
 	try {
@@ -101,7 +97,7 @@ export const createEvent = async (input: CreateEventInput, createdByEmail: strin
 			INSERT INTO events (slug, name, subtitle, event_date, feedback_deadline, intro_text, created_by_email)
 			VALUES (?,?,?,?,?,?,?) RETURNING event_id`;
 		const res = await conn.query(query, [
-			slug, input.name, input.subtitle || null, input.eventDate, toMysqlDatetime(deadline),
+			slug, input.name, input.subtitle || null, input.eventDate, formatDatetime(deadline),
 			input.introText || null, createdByEmail
 		]);
 		await conn.commit();
diff --git a/src/models/feedback/admin/questions.admin.router.ts b/src/models/feedback/admin/questions.admin.router.ts
index bea0db8..75fefb6 100644
--- a/src/models/feedback/admin/questions.admin.router.ts
+++ b/src/models/feedback/admin/questions.admin.router.ts
@@ -2,25 +2,14 @@
  * Required External Modules and Interfaces
  */
 import express, {Request, Response} from 'express';
-import {Guid} from 'guid-typescript';
-import logger from '../../../middleware/logger';
 import * as QuestionsAdminService from './questions.admin.service';
+import {sendServerError} from '../feedback.errors';
 
 /**
  * Router Definition
  */
 export const questionsAdminRouter = express.Router();
 
-const sendServerError = (res: Response, e: any) => {
-	let errorGuid = Guid.create().toString();
-	logger.error('Error handling a request: ' + e.message, {reference: errorGuid});
-	res.status(500).send({
-		'status': 'PROCESSING_ERROR',
-		'message': 'Internal Server Error. Try again later.',
-		'reference': errorGuid
-	});
-};
-
 /**
  * @swagger
  * /feedback/admin/questions:
diff --git a/src/models/feedback/admin/reports.admin.interface.ts b/src/models/feedback/admin/reports.admin.interface.ts
index 91abdfb..a94e6ad 100644
--- a/src/models/feedback/admin/reports.admin.interface.ts
+++ b/src/models/feedback/admin/reports.admin.interface.ts
@@ -58,6 +58,7 @@ export interface EventReport {
 		sent: number;
 		pending: number;
 		failed: number;
+		skipped: number;
 	};
 }
 
diff --git a/src/models/feedback/admin/reports.admin.router.ts b/src/models/feedback/admin/reports.admin.router.ts
index eed0244..6e82ad7 100644
--- a/src/models/feedback/admin/reports.admin.router.ts
+++ b/src/models/feedback/admin/reports.admin.router.ts
@@ -2,27 +2,16 @@
  * Required External Modules and Interfaces
  */
 import express, {Request, Response} from 'express';
-import {Guid} from 'guid-typescript';
-import logger from '../../../middleware/logger';
 import * as ReportsAdminService from './reports.admin.service';
 import * as CsvService from './csv.service';
 import * as EventsAdminService from './events.admin.service';
+import {sendServerError} from '../feedback.errors';
 
 /**
  * Router Definition
  */
 export const reportsAdminRouter = express.Router();
 
-const sendServerError = (res: Response, e: any) => {
-	let errorGuid = Guid.create().toString();
-	logger.error('Error handling a request: ' + e.message, {reference: errorGuid});
-	res.status(500).send({
-		'status': 'PROCESSING_ERROR',
-		'message': 'Internal Server Error. Try again later.',
-		'reference': errorGuid
-	});
-};
-
 /**
  * @swagger
  * /feedback/admin/events/{eventId}/report:
diff --git a/src/models/feedback/admin/reports.admin.service.ts b/src/models/feedback/admin/reports.admin.service.ts
index 5210e21..876fc9f 100644
--- a/src/models/feedback/admin/reports.admin.service.ts
+++ b/src/models/feedback/admin/reports.admin.service.ts
@@ -16,7 +16,7 @@ export const aggregateReport = (
 	submissionStats: {totalSubmissions: number; firstSubmissionAt: string | null; lastSubmissionAt: string | null},
 	answerRows: AnswerRow[],
 	guestBookCount: number,
-	newsletterCounts: {total: number; sent: number; pending: number; failed: number}
+	newsletterCounts: {total: number; sent: number; pending: number; failed: number; skipped: number}
 ): EventReport => {
 	const groupKey = (row: AnswerRow) => `${row.questionId ?? 'null'}::${row.questionLabel}`;
 
@@ -137,13 +137,14 @@ export const getReport = async (eventId: number): Promise<EventReport | null> =>
 			`SELECT sync_status, COUNT(*) as cnt FROM newsletter_signups WHERE event_id = ? GROUP BY sync_status`,
 			[eventId]
 		);
-		const newsletterCounts = {total: 0, sent: 0, pending: 0, failed: 0};
+		const newsletterCounts = {total: 0, sent: 0, pending: 0, failed: 0, skipped: 0};
 		for (const row of newsletterRows) {
 			const cnt = Number(row.cnt);
 			newsletterCounts.total += cnt;
 			if (row.sync_status === 'SENT') newsletterCounts.sent = cnt;
 			else if (row.sync_status === 'PENDING') newsletterCounts.pending = cnt;
 			else if (row.sync_status === 'FAILED') newsletterCounts.failed = cnt;
+			else if (row.sync_status === 'SKIPPED') newsletterCounts.skipped = cnt;
 		}
 
 		return aggregateReport(
diff --git a/src/models/feedback/admin/songs.admin.router.ts b/src/models/feedback/admin/songs.admin.router.ts
index ad0faaf..52b9f71 100644
--- a/src/models/feedback/admin/songs.admin.router.ts
+++ b/src/models/feedback/admin/songs.admin.router.ts
@@ -2,9 +2,8 @@
  * Required External Modules and Interfaces
  */
 import express, {Request, Response} from 'express';
-import {Guid} from 'guid-typescript';
-import logger from '../../../middleware/logger';
 import * as SongsAdminService from './songs.admin.service';
+import {sendServerError} from '../feedback.errors';
 
 /**
  * Router Definition
@@ -80,13 +79,7 @@ songsAdminRouter.put('/:songId', async (req: Request, res: Response) => {
 		}
 		res.status(200).send({status: 'OK'});
 	} catch (e: any) {
-		let errorGuid = Guid.create().toString();
-		logger.error('Error handling a request: ' + e.message, {reference: errorGuid});
-		res.status(500).send({
-			'status': 'PROCESSING_ERROR',
-			'message': 'Internal Server Error. Try again later.',
-			'reference': errorGuid
-		});
+		sendServerError(res, e);
 	}
 });
 
@@ -99,12 +92,6 @@ songsAdminRouter.delete('/:songId', async (req: Request, res: Response) => {
 		}
 		res.status(204).send();
 	} catch (e: any) {
-		let errorGuid = Guid.create().toString();
-		logger.error('Error handling a request: ' + e.message, {reference: errorGuid});
-		res.status(500).send({
-			'status': 'PROCESSING_ERROR',
-			'message': 'Internal Server Error. Try again later.',
-			'reference': errorGuid
-		});
+		sendServerError(res, e);
 	}
 });
diff --git a/src/models/feedback/feedback.auth.ts b/src/models/feedback/feedback.auth.ts
index d569ef7..91cb292 100644
--- a/src/models/feedback/feedback.auth.ts
+++ b/src/models/feedback/feedback.auth.ts
@@ -1,7 +1,6 @@
 import express from 'express';
-import {Guid} from 'guid-typescript';
-import logger from '../../middleware/logger';
 import * as UserService from '../calendar/users/users.service';
+import {sendServerError} from './feedback.errors';
 
 /**
  * This file is the ONLY place in the feedback module that knows how admin
@@ -74,12 +73,6 @@ export const requireAdminAuth: express.RequestHandler = async (req, res, next) =
 		res.locals.admin = identity;
 		next();
 	} catch (e: any) {
-		let errorGuid = Guid.create().toString();
-		logger.error('Error handling a request: ' + e.message, {reference: errorGuid});
-		res.status(500).send({
-			'status': 'PROCESSING_ERROR',
-			'message': 'Internal Server Error. Try again later.',
-			'reference': errorGuid
-		});
+		sendServerError(res, e);
 	}
 };
diff --git a/src/models/feedback/feedback.dates.ts b/src/models/feedback/feedback.dates.ts
new file mode 100644
index 0000000..d39cb65
--- /dev/null
+++ b/src/models/feedback/feedback.dates.ts
@@ -0,0 +1,13 @@
+/**
+ * Formats a Date using its local getters (not toISOString/UTC), so the
+ * wall-clock time the server is running in is what gets stored/displayed -
+ * never silently shifted by a UTC conversion. Used both for MySQL DATETIME
+ * literals (events.admin.service.ts) and CSV export (csv.service.ts): same
+ * requirement, same format, in either context.
+ */
+export const formatDatetime = (value: Date | string | null): string => {
+	if (!value) return '';
+	const d = value instanceof Date ? value : new Date(value);
+	const pad = (n: number) => String(n).padStart(2, '0');
+	return `${d.getFullYear()}-${pad(d.getMonth() + 1)}-${pad(d.getDate())} ${pad(d.getHours())}:${pad(d.getMinutes())}:${pad(d.getSeconds())}`;
+};
diff --git a/src/models/feedback/feedback.errors.ts b/src/models/feedback/feedback.errors.ts
new file mode 100644
index 0000000..58b003d
--- /dev/null
+++ b/src/models/feedback/feedback.errors.ts
@@ -0,0 +1,18 @@
+import {Response} from 'express';
+import {Guid} from 'guid-typescript';
+import logger from '../../middleware/logger';
+
+/**
+ * The feedback module's standard catch-block response: log with a
+ * reference guid, never leak the real error message to the client. Every
+ * router in this module follows this exact convention (see CLAUDE.md).
+ */
+export const sendServerError = (res: Response, e: any): void => {
+	const errorGuid = Guid.create().toString();
+	logger.error('Error handling a request: ' + e.message, {reference: errorGuid});
+	res.status(500).send({
+		status: 'PROCESSING_ERROR',
+		message: 'Internal Server Error. Try again later.',
+		reference: errorGuid
+	});
+};
diff --git a/src/models/feedback/public/public.router.ts b/src/models/feedback/public/public.router.ts
index 2960392..e5df0b3 100644
--- a/src/models/feedback/public/public.router.ts
+++ b/src/models/feedback/public/public.router.ts
@@ -2,11 +2,11 @@
  * Required External Modules and Interfaces
  */
 import express, {Request, Response} from 'express';
-import {Guid} from 'guid-typescript';
 import logger from '../../../middleware/logger';
 import {getEligibleEvents, getEventConfigBySlug} from './events.public.service';
 import {submitFeedback} from './submissions.service';
 import {hashIp, isRateLimited, recordSubmission} from '../feedback.ratelimit';
+import {sendServerError} from '../feedback.errors';
 
 /**
  * Router Definition
@@ -51,13 +51,7 @@ publicRouter.get('/events', async (req: Request, res: Response) => {
 		const events = await getEligibleEvents();
 		res.status(200).send(events);
 	} catch (e: any) {
-		let errorGuid = Guid.create().toString();
-		logger.error('Error handling a request: ' + e.message, {reference: errorGuid});
-		res.status(500).send({
-			'status': 'PROCESSING_ERROR',
-			'message': 'Internal Server Error. Try again later.',
-			'reference': errorGuid
-		});
+		sendServerError(res, e);
 	}
 });
 
@@ -106,13 +100,7 @@ publicRouter.get('/events/:slug', async (req: Request, res: Response) => {
 		}
 		res.status(200).send(result.event);
 	} catch (e: any) {
-		let errorGuid = Guid.create().toString();
-		logger.error('Error handling a request: ' + e.message, {reference: errorGuid});
-		res.status(500).send({
-			'status': 'PROCESSING_ERROR',
-			'message': 'Internal Server Error. Try again later.',
-			'reference': errorGuid
-		});
+		sendServerError(res, e);
 	}
 });
 
@@ -166,7 +154,7 @@ publicRouter.post('/events/:slug/submissions', async (req: Request, res: Respons
 		// nothing, stay silent about it having failed.
 		if (isHoneypotTriggered(body)) {
 			logger.info('Feedback honeypot triggered', {slug: req.params.slug});
-			res.status(201).send({submissionId: -1});
+			res.status(201).send({submissionId: -1, newsletterDropped: false});
 			return;
 		}
 
@@ -196,16 +184,10 @@ publicRouter.post('/events/:slug/submissions', async (req: Request, res: Respons
 				res.status(400).send({status: 'EMPTY_SUBMISSION'});
 				return;
 			case 'OK':
-				res.status(201).send({submissionId: result.submissionId});
+				res.status(201).send({submissionId: result.submissionId, newsletterDropped: result.newsletterDropped});
 				return;
 		}
 	} catch (e: any) {
-		let errorGuid = Guid.create().toString();
-		logger.error('Error handling a request: ' + e.message, {reference: errorGuid});
-		res.status(500).send({
-			'status': 'PROCESSING_ERROR',
-			'message': 'Internal Server Error. Try again later.',
-			'reference': errorGuid
-		});
+		sendServerError(res, e);
 	}
 });
diff --git a/src/models/feedback/public/submission.interface.ts b/src/models/feedback/public/submission.interface.ts
index 58b39a7..933d098 100644
--- a/src/models/feedback/public/submission.interface.ts
+++ b/src/models/feedback/public/submission.interface.ts
@@ -62,6 +62,9 @@
  *         submissionId:
  *           type: integer
  *           example: 91
+ *         newsletterDropped:
+ *           type: boolean
+ *           description: True if the newsletter opt-in was present but failed validation (e.g. a malformed email) - the rest of the submission still saved.
  */
 
 export interface RatingInput {
diff --git a/src/models/feedback/public/submissions.service.ts b/src/models/feedback/public/submissions.service.ts
index 9d74c02..8f13e4e 100644
--- a/src/models/feedback/public/submissions.service.ts
+++ b/src/models/feedback/public/submissions.service.ts
@@ -137,7 +137,7 @@ export const validateNewsletter = (input?: NewsletterInput): ValidatedNewsletter
 };
 
 export type SubmitResult =
-	| { status: 'OK'; submissionId: number }
+	| { status: 'OK'; submissionId: number; newsletterDropped: boolean }
 	| { status: 'NOT_FOUND' }
 	| { status: 'CLOSED' }
 	| { status: 'EMPTY' };
@@ -160,6 +160,12 @@ export const submitFeedback = async (slug: string, body: SubmissionRequestBody,
 	const answerRows = validateAnswers(body.answers || [], questionsById, songTitleById);
 	const guestBook = validateGuestBook(body.guestBook);
 	const newsletter = validateNewsletter(body.newsletter);
+	// body.newsletter is only sent at all when the visitor had the opt-in
+	// checkbox on (see FeedbackForm.tsx), so a present-but-invalid block
+	// (e.g. a mistyped email) is distinguishable from "didn't opt in" - the
+	// rest of the submission still saves, but the client can tell the
+	// visitor their newsletter signup specifically didn't go through.
+	const newsletterDropped = !!body.newsletter && !newsletter;
 
 	if (answerRows.length === 0 && !guestBook && !newsletter) {
 		return {status: 'EMPTY'};
@@ -213,7 +219,7 @@ export const submitFeedback = async (slug: string, body: SubmissionRequestBody,
 			});
 		}
 
-		return {status: 'OK', submissionId};
+		return {status: 'OK', submissionId, newsletterDropped};
 	} catch (err) {
 		await conn.rollback();
 		throw err;
diff --git a/test/feedback/csv.service.test.ts b/test/feedback/csv.service.test.ts
index 950f9dc..df00170 100644
--- a/test/feedback/csv.service.test.ts
+++ b/test/feedback/csv.service.test.ts
@@ -1,4 +1,5 @@
-import {escapeCsvField, formatDatetime} from '../../src/models/feedback/admin/csv.service';
+import {escapeCsvField} from '../../src/models/feedback/admin/csv.service';
+import {formatDatetime} from '../../src/models/feedback/feedback.dates';
 
 describe('escapeCsvField', () => {
 	it('passes plain text through unchanged', () => {
diff --git a/test/feedback/reports.admin.service.test.ts b/test/feedback/reports.admin.service.test.ts
index 4af9d7c..630960f 100644
--- a/test/feedback/reports.admin.service.test.ts
+++ b/test/feedback/reports.admin.service.test.ts
@@ -2,7 +2,7 @@ import {aggregateReport} from '../../src/models/feedback/admin/reports.admin.ser
 import {AnswerRow} from '../../src/models/feedback/admin/reports.admin.interface';
 
 const eventMeta = {eventId: 1, name: 'Sommerkonzert', eventDate: '2026-08-01', feedbackDeadline: '2026-08-15T23:59:59'};
-const emptyNewsletter = {total: 0, sent: 0, pending: 0, failed: 0};
+const emptyNewsletter = {total: 0, sent: 0, pending: 0, failed: 0, skipped: 0};
 
 const row = (overrides: Partial<AnswerRow>): AnswerRow => ({
 	submissionId: 1,
@@ -90,13 +90,13 @@ describe('aggregateReport - top-level fields', () => {
 			{totalSubmissions: 42, firstSubmissionAt: '2026-08-02T10:00:00.000Z', lastSubmissionAt: '2026-08-10T18:00:00.000Z'},
 			[],
 			7,
-			{total: 10, sent: 6, pending: 2, failed: 2}
+			{total: 10, sent: 6, pending: 2, failed: 1, skipped: 1}
 		);
 		expect(report.totalSubmissions).toBe(42);
 		expect(report.firstSubmissionAt).toBe('2026-08-02T10:00:00.000Z');
 		expect(report.lastSubmissionAt).toBe('2026-08-10T18:00:00.000Z');
 		expect(report.guestBookCount).toBe(7);
-		expect(report.newsletter).toEqual({total: 10, sent: 6, pending: 2, failed: 2});
+		expect(report.newsletter).toEqual({total: 10, sent: 6, pending: 2, failed: 1, skipped: 1});
 		expect(report.event).toEqual(eventMeta);
 	});