feat: try to detect mailing lists as event attendees

src/components/Editor/Invitees/InviteesListSearch.vue

@@ -47,6 +47,10 @@
 					<div v-if="option.type === 'circle' || option.type === 'contactsgroup'">
 						{{ option.subtitle }}
 					</div>
+					<div v-else-if="option.looksLikeMailingList" class="invitees-search-list-item__warning">
+						<AlertCircleOutline :size="14" />
+						{{ $t('calendar', 'This might be a mailing list. Invitations will not work.') }}
+					</div>
 				</div>
 			</div>
 		</template>
@@ -62,13 +66,14 @@ import {
 	NcSelect,
 } from '@nextcloud/vue'
 import debounce from 'debounce'
+import AlertCircleOutline from 'vue-material-design-icons/AlertCircleOutline.vue'
 import GoogleCirclesCommunitiesIcon from 'vue-material-design-icons/GoogleCirclesCommunities.vue'
 import {
 	circleGetMembers,
 	circleSearchByName,
 } from '@/services/circleService.js'
 import isCirclesEnabled from '@/services/isCirclesEnabled.js'
-import { removeMailtoPrefix } from '@/utils/attendee.js'
+import { looksLikeMailingList, removeMailtoPrefix } from '@/utils/attendee.js'
 import logger from '@/utils/logger.js'
 import { randomId } from '@/utils/randomId.js'
 
@@ -78,6 +83,7 @@ export default {
 		Avatar,
 		NcSelect,
 		GoogleCirclesCommunitiesIcon,
+		AlertCircleOutline,
 	},
 
 	props: {
@@ -154,6 +160,7 @@ export default {
 							timezoneId: null,
 							hasMultipleEMails: false,
 							dropdownName: query,
+							looksLikeMailingList: looksLikeMailingList(query),
 						})
 					}
 				}
@@ -290,6 +297,7 @@ export default {
 						timezoneId: result.tzid,
 						hasMultipleEMails,
 						dropdownName: name + ' ' + email,
+						looksLikeMailingList: looksLikeMailingList(email),
 					})
 				})
 
@@ -330,5 +338,13 @@ export default {
 
 :deep(.vs__search::placeholder) {
 	text-overflow: ellipsis;
+
+}
+
+.invitees-search-list-item__warning {
+	display: flex;
+	align-items: center;
+	gap: 4px;
+	color: var(--color-warning);
 }
 </style>

src/utils/attendee.js

@@ -84,6 +84,94 @@ export function getRoomAttendees(attendees) {
 	return attendees.filter((attendee) => attendee?.attendeeProperty?.userType === 'ROOM')
 }
 
+/*
+ * Heuristically check if an email address looks like a mailing list address
+ *
+ * @param {string} email Email address to check (with or without mailto: prefix)
+ * @return {boolean} True if the address looks like a mailing list
+ */
+export function looksLikeMailingList(email) {
+	if (typeof email !== 'string') {
+		return false
+	}
+
+	const address = removeMailtoPrefix(email).toLowerCase()
+	const atIndex = address.indexOf('@')
+	if (atIndex === -1) {
+		return false
+	}
+
+	const local = address.slice(0, atIndex)
+	const domain = address.slice(atIndex + 1)
+
+	const exactMatches = new Set([
+		'list',
+		'lists',
+		'ml',
+		'announce',
+		'announcements',
+		'noreply',
+		'no-reply',
+		'newsletter',
+		'newsletters',
+		'mailer-daemon',
+		'postmaster',
+		'sympa',
+		'majordomo',
+		'listserv',
+		'mailman',
+		'dmarc',
+		'bounce',
+		'bounces',
+		'subscribe',
+		'unsubscribe',
+	])
+	if (exactMatches.has(local)) {
+		return true
+	}
+
+	const suffixes = [
+		'-bounces',
+		'-request',
+		'-subscribe',
+		'-unsubscribe',
+		'-owner',
+		'-help',
+		'-announce',
+		'-devel',
+		'-discuss',
+		'-commits',
+		'-bugs',
+		'-patches',
+		'-users',
+		'-list',
+		'+bounces',
+		'+subscribe',
+	]
+	if (suffixes.some((s) => local.endsWith(s))) {
+		return true
+	}
+
+	const knownDomains = new Set([
+		'googlegroups.com',
+		'groups.io',
+		'freelists.org',
+		'yahoogroups.com',
+		'listserv.com',
+		'topica.com',
+	])
+	if (knownDomains.has(domain)) {
+		return true
+	}
+
+	const knownSubdomainPrefixes = ['lists.', 'ml.', 'listserv.', 'mailman.', 'sympa.']
+	if (knownSubdomainPrefixes.some((p) => domain.startsWith(p))) {
+		return true
+	}
+
+	return false
+}
+
 /**
  * Check if the current user is an attendee
  *

tests/javascript/unit/utils/attendee.test.js

@@ -7,6 +7,7 @@ import {
 	addMailtoPrefix,
 	getRoomAttendees,
 	isPendingResourceBooking,
+	looksLikeMailingList,
 	organizerDisplayName,
 	removeMailtoPrefix,
 } from '@/utils/attendee.js'
@@ -37,6 +38,51 @@ describe('utils/attendee test suite', () => {
 		expect(addMailtoPrefix(undefined)).toEqual('mailto:')
 	})
 
+	describe('looksLikeMailingList', () => {
+		it('detects exact local-part matches', () => {
+			expect(looksLikeMailingList('announce@example.com')).toBe(true)
+			expect(looksLikeMailingList('mailman@example.org')).toBe(true)
+			expect(looksLikeMailingList('noreply@example.com')).toBe(true)
+			expect(looksLikeMailingList('lists@example.com')).toBe(true)
+		})
+
+		it('detects local-part suffix matches', () => {
+			expect(looksLikeMailingList('dev-bounces@example.org')).toBe(true)
+			expect(looksLikeMailingList('project-request@example.com')).toBe(true)
+			expect(looksLikeMailingList('calendar-users@example.com')).toBe(true)
+			expect(looksLikeMailingList('app+bounces@example.com')).toBe(true)
+		})
+
+		it('detects known mailing list domains', () => {
+			expect(looksLikeMailingList('group@googlegroups.com')).toBe(true)
+			expect(looksLikeMailingList('list@groups.io')).toBe(true)
+			expect(looksLikeMailingList('user@freelists.org')).toBe(true)
+		})
+
+		it('detects known mailing list subdomains', () => {
+			expect(looksLikeMailingList('user@lists.nextcloud.com')).toBe(true)
+			expect(looksLikeMailingList('someone@mailman.apache.org')).toBe(true)
+			expect(looksLikeMailingList('foo@sympa.example.com')).toBe(true)
+		})
+
+		it('handles mailto: prefix', () => {
+			expect(looksLikeMailingList('mailto:announce@example.com')).toBe(true)
+			expect(looksLikeMailingList('mailto:john@example.com')).toBe(false)
+		})
+
+		it('returns false for regular email addresses', () => {
+			expect(looksLikeMailingList('john@example.com')).toBe(false)
+			expect(looksLikeMailingList('dev@example.com')).toBe(false)
+			expect(looksLikeMailingList('alice@company.com')).toBe(false)
+		})
+
+		it('returns false for invalid input', () => {
+			expect(looksLikeMailingList('notanemail')).toBe(false)
+			expect(looksLikeMailingList(null)).toBe(false)
+			expect(looksLikeMailingList(undefined)).toBe(false)
+		})
+	})
+
 	it('should extract a display name of an organizer', () => {
 		const commonName = 'My Name'
 		const uri = 'uri@test.com'