diff --git a/appinfo/routes.php b/appinfo/routes.php
index 0f538e7866..d25b478db8 100644
--- a/appinfo/routes.php
+++ b/appinfo/routes.php
@@ -89,6 +89,26 @@
 			'url' => '/api/accounts/{id}/quota',
 			'verb' => 'GET'
 		],
+		[
+			'name' => 'contactIntegration#autoComplete',
+			'url' => '/api/contactIntegration/autoComplete/{term}',
+			'verb' => 'GET'
+		],
+		[
+			'name' => 'contactIntegration#addMail',
+			'url' => '/api/contactIntegration/add',
+			'verb' => 'PUT'
+		],
+		[
+			'name' => 'contactIntegration#newContact',
+			'url' => '/api/contactIntegration/new',
+			'verb' => 'PUT'
+		],
+		[
+			'name' => 'contactIntegration#match',
+			'url' => '/api/contactIntegration/match/{mail}',
+			'verb' => 'GET'
+		],
 		[
 			'name' => 'mailboxes#patch',
 			'url' => '/api/mailboxes/{id}',
diff --git a/lib/Controller/ContactIntegrationController.php b/lib/Controller/ContactIntegrationController.php
new file mode 100644
index 0000000000..81f49bb7a3
--- /dev/null
+++ b/lib/Controller/ContactIntegrationController.php
@@ -0,0 +1,99 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @author Kristian Lebold <kristian@lebold.info>
+ *
+ * Mail
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\Mail\Controller;
+
+use OCA\Mail\Service\ContactIntegration\ContactIntegrationService;
+use OCP\AppFramework\Controller;
+use OCP\AppFramework\Http;
+use OCP\AppFramework\Http\JSONResponse;
+use OCP\IRequest;
+
+class ContactIntegrationController extends Controller {
+
+	/** @var ContactIntegrationService */
+	private $service;
+
+	public function __construct(string $appName,
+								IRequest $request,
+								ContactIntegrationService $service) {
+		parent::__construct($appName, $request);
+
+		$this->service = $service;
+	}
+
+	/**
+	 * @NoAdminRequired
+	 * @TrapError
+	 *
+	 * @param string $mail
+	 * @return JSONResponse
+	 */
+	public function match(string $mail): JSONResponse {
+		return new JSONResponse($this->service->findMatches($mail));
+	}
+
+	/**
+	 * @NoAdminRequired
+	 * @TrapError
+	 *
+	 * @param string $uid
+	 * @param string $mail
+	 * @return JSONResponse
+	 */
+	public function addMail(string $uid = null, string $mail = null): JSONResponse {
+		$res = $this->service->addEMailToContact($uid, $mail);
+		if ($res === null) {
+			return new JSONResponse([], Http::STATUS_NOT_FOUND);
+		}
+		return new JSONResponse($res);
+	}
+
+	/**
+	 * @NoAdminRequired
+	 * @TrapError
+	 *
+	 * @param string $name
+	 * @param string $mail
+	 * @return JSONResponse
+	 */
+	public function newContact(string $contactName = null, string $mail = null): JSONResponse {
+		$res = $this->service->newContact($contactName, $mail);
+		if ($res === null) {
+			return new JSONResponse([], Http::STATUS_NOT_ACCEPTABLE);
+		}
+		return new JSONResponse($res);
+	}
+
+	/**
+	 * @NoAdminRequired
+	 * @TrapError
+	 *
+	 * @param string $term
+	 * @return JSONResponse
+	 */
+	public function autoComplete(string $term): JSONResponse {
+		$res = $this->service->autoComplete($term);
+		return new JSONResponse($res);
+	}
+}
diff --git a/lib/Service/ContactIntegration/ContactIntegrationService.php b/lib/Service/ContactIntegration/ContactIntegrationService.php
new file mode 100644
index 0000000000..3579a3ebd8
--- /dev/null
+++ b/lib/Service/ContactIntegration/ContactIntegrationService.php
@@ -0,0 +1,53 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * @author Kristian Lebold <kristian@lebold.info>
+ *
+ * Mail
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCA\Mail\Service\ContactIntegration;
+
+use OCA\Mail\Service\ContactsIntegration;
+
+class ContactIntegrationService {
+
+	/** @var ContactsIntegration */
+	private $contactsIntegration;
+
+	public function __construct(ContactsIntegration $ci) {
+		$this->contactsIntegration = $ci;
+	}
+
+	public function findMatches(string $mail): array {
+		$matches = $this->contactsIntegration->getContactsWithMail($mail);
+		return $matches;
+	}
+
+	public function addEMailToContact(string $uid, string $mail): ?array {
+		return $this->contactsIntegration->addEmailToContact($uid, $mail);
+	}
+
+	public function newContact(string $name, string $mail): ?array {
+		return $this->contactsIntegration->newContact($name, $mail);
+	}
+
+	public function autoComplete(string $term): array {
+		return $this->contactsIntegration->getContactsWithName($term);
+	}
+}
diff --git a/lib/Service/ContactsIntegration.php b/lib/Service/ContactsIntegration.php
index 2f5a1f1393..52c32582fc 100644
--- a/lib/Service/ContactsIntegration.php
+++ b/lib/Service/ContactsIntegration.php
@@ -118,4 +118,109 @@ private function getPhotoUri(string $raw) {
 			return null;
 		}
 	}
+
+	/**
+	 * Adds a new email to an existing Contact
+	 *
+	 * @param string $uid
+	 * @param string $mailAddr
+	 * @param string $type
+	 * @return array|null
+	 */
+	public function addEmailToContact(string $uid, string $mailAddr, string $type = 'HOME') {
+		if (!$this->contactsManager->isEnabled()) {
+			return null;
+		}
+
+		$result = $this->contactsManager->search($uid, ['UID'], ['types' => true, 'limit' => 1]);
+		
+		if (count($result) !== 1) {
+			return null; // no match
+		}
+		
+		$newEntry = [
+			'type' => $type,
+			'value' => $mailAddr
+		];
+		
+		$match = $result[0];
+		$email = $match['EMAIL'] ?? [];
+		if (!empty($email) && !is_array($email[0])) {
+			$email = [$email];
+		}
+		$email[] = $newEntry;
+		$match['EMAIL'] = $email;
+
+		$updatedContact = $this->contactsManager->createOrUpdate($match, $match['addressbook-key']);
+		return $updatedContact;
+	}
+
+	/**
+	 * Adds a new contact with the specified email to an addressbook
+	 *
+	 * @param string $uid
+	 * @param string $mailAddr
+	 * @param string $addressbook
+	 * @return array|null
+	 */
+	public function newContact(string $name, string $mailAddr, string $type = 'HOME', string $addressbook = null) {
+		if (!$this->contactsManager->isEnabled()) {
+			return null;
+		}
+
+		if (!isset($addressbook)) {
+			$addressbook = key($this->contactsManager->getUserAddressBooks());
+		}
+
+		$contact = [
+			'FN' => $name,
+			'EMAIL' => [
+				[
+					'type' => $type,
+					'value' => $mailAddr
+				]
+			]
+		];
+		$createdContact = $this->contactsManager->createOrUpdate($contact, $addressbook);
+		return $createdContact;
+	}
+
+	private function doSearch($term, $fields): array {
+		$allowSystemUsers = $this->config->getAppValue('core', 'shareapi_allow_share_dialog_user_enumeration', 'no') === 'yes';
+
+		$result = $this->contactsManager->search($term, $fields);
+		$matches = [];
+		foreach ($result as $r) {
+			if (!$allowSystemUsers && isset($r['isLocalSystemBook']) && $r['isLocalSystemBook']) {
+				continue;
+			}
+			$id = $r['UID'];
+			$fn = $r['FN'];
+			$matches[] = [
+				'id' => $id,
+				'label' => $fn,
+			];
+		}
+		return $matches;
+	}
+
+	/**
+	 * Extracts all Contacts with the specified mail address
+	 *
+	 * @param string $mailAddr
+	 * @return array
+	 */
+	public function getContactsWithMail(string $mailAddr) {
+		return $this->doSearch($mailAddr, ['EMAIL']);
+	}
+
+	/**
+	 * Extracts all Contacts with the specified name
+	 *
+	 * @param string $mailAddr
+	 * @return array
+	 */
+	public function getContactsWithName($name) {
+		return $this->doSearch($name, ['FN']);
+	}
 }
diff --git a/src/components/RecipientBubble.vue b/src/components/RecipientBubble.vue
index 897f542a5a..48bfe3afb8 100644
--- a/src/components/RecipientBubble.vue
+++ b/src/components/RecipientBubble.vue
@@ -20,23 +20,92 @@
   -->
 
 <template>
-	<UserBubble :display-name="label"
-		:avatar-image="avatarUrlAbsolute"
-		@click="onClick">
-		<span class="user-bubble-email">{{ email }}</span>
-	</UserBubble>
+	<Popover trigger="click" class="contact-popover">
+		<UserBubble slot="trigger"
+			:display-name="label"
+			:avatar-image="avatarUrlAbsolute"
+			@click="onClickOpenContactDialog">
+			<span class="user-bubble-email">{{ email }}</span>
+		</UserBubble>
+		<template>
+			<div class="contact-wrapper">
+				<div v-if="contactsWithEmail && contactsWithEmail.length > 0" class="contact-existing">
+					<span class="icon-details">
+						{{ t('mail', 'Contacts with this address') }}:
+					</span>
+					<span>
+						{{ contactsWithEmailComputed }}
+					</span>
+				</div>
+				<div v-if="selection === ContactSelectionStateEnum.select">
+					<a class="icon-reply" @click="onClickReply">
+						<span class="action-label">{{ t('mail', 'Reply') }}</span>
+					</a>
+					<a class="icon-user" @click="selection = ContactSelectionStateEnum.existing">
+						<span class="action-label">{{ t('mail', 'Add to Contact') }}</span>
+					</a>
+					<a class="icon-add" @click="selection = ContactSelectionStateEnum.new">
+						<span class="action-label">{{ t('mail', 'New Contact') }}</span>
+					</a>
+				</div>
+				<div v-else class="contact-input-wrapper">
+					<Multiselect
+						v-if="selection === ContactSelectionStateEnum.existing"
+						id="contact-selection"
+						ref="contact-selection-label"
+						v-model="selectedContact"
+						:options="selectableContacts"
+						:taggable="true"
+						label="label"
+						track-by="label"
+						:multiple="false"
+						:placeholder="t('name', 'Contact name …')"
+						:clear-on-select="false"
+						:show-no-options="false"
+						:preserve-search="true"
+						@search-change="onAutocomplete" />
+
+					<input v-else-if="selection === ContactSelectionStateEnum.new" v-model="newContactName">
+				</div>
+				<div v-if="selection !== ContactSelectionStateEnum.select">
+					<a class="icon-close" type="button" @click="selection = ContactSelectionStateEnum.select">
+						{{ t('mail', 'Go back') }}
+					</a>
+					<a
+						v-close-popover
+						:disabled="addButtonDisabled"
+						class="icon-checkmark"
+						type="button"
+						@click="onClickAddToContact">
+						{{ t('mail', 'Add') }}
+					</a>
+				</div>
+			</div>
+		</template>
+	</Popover>
 </template>
 
 <script>
 import { generateUrl } from '@nextcloud/router'
 import UserBubble from '@nextcloud/vue/dist/Components/UserBubble'
+import Popover from '@nextcloud/vue/dist/Components/Popover'
+import Multiselect from '@nextcloud/vue/dist/Components/Multiselect'
 
 import { fetchAvatarUrlMemoized } from '../service/AvatarService'
+import { addToContact, findMatches, newContact, autoCompleteByName } from '../service/ContactIntegrationService'
+import uniqBy from 'lodash/fp/uniqBy'
+import debouncePromise from 'debounce-promise'
+
+const debouncedSearch = debouncePromise(autoCompleteByName, 500)
+
+const ContactSelectionStateEnum = Object.freeze({ new: 1, existing: 2, select: 3 })
 
 export default {
 	name: 'RecipientBubble',
 	components: {
 		UserBubble,
+		Popover,
+		Multiselect,
 	},
 	props: {
 		email: {
@@ -51,6 +120,14 @@ export default {
 	data() {
 		return {
 			avatarUrl: undefined,
+			loadingContacts: false,
+			contactsWithEmail: [],
+			autoCompleteContacts: [],
+			selectedContact: '',
+			newContactName: '',
+			ContactSelectionStateEnum,
+			selection: ContactSelectionStateEnum.select,
+			isContactPopoverOpen: false,
 		}
 	},
 	computed: {
@@ -65,6 +142,21 @@ export default {
 			// Make it an absolute URL because the user bubble component doesn't work with relative URLs
 			return window.location.protocol + '//' + window.location.host + generateUrl(this.avatarUrl)
 		},
+		selectableContacts() {
+			return this.autoCompleteContacts
+				.map((contact) => ({ ...contact, label: contact.label }))
+		},
+		contactsWithEmailComputed() {
+			let additional = ''
+			if (this.contactsWithEmail && this.contactsWithEmail.length > 3) {
+				additional = ` + ${this.contactsWithEmail.length - 3}`
+			}
+			return this.contactsWithEmail.slice(0, 3).map(e => e.label).join(', ').concat(additional)
+		},
+		addButtonDisabled() {
+			return !((this.selection === ContactSelectionStateEnum.existing && this.selectedContact)
+					|| (this.selection === ContactSelectionStateEnum.new && this.newContactName.trim() !== ''))
+		},
 	},
 	async mounted() {
 		try {
@@ -74,9 +166,10 @@ export default {
 				error,
 			})
 		}
+		this.newContactName = this.label
 	},
 	methods: {
-		onClick() {
+		onClickReply() {
 			this.$router.push({
 				name: 'message',
 				params: {
@@ -88,6 +181,34 @@ export default {
 				},
 			})
 		},
+		onClickOpenContactDialog() {
+			if (this.contactsWithEmail.length === 0) { // TODO fix me
+				findMatches(this.email).then(res => {
+					if (res && res.length > 0) {
+						this.contactsWithEmail = res
+					}
+				})
+			}
+		},
+		onClickAddToContact() {
+			if (this.selection === ContactSelectionStateEnum.new) {
+				if (this.newContactName !== '') {
+					newContact(this.newContactName.trim(), this.email).then(res => console.debug('ContactIntegration', res))
+				}
+			} else if (this.selection === ContactSelectionStateEnum.existing) {
+				if (this.selectedContact) {
+					addToContact(this.selectedContact.id, this.email).then(res => console.debug('ContactIntegration', res))
+				}
+			}
+		},
+		onAutocomplete(term) {
+			if (term === undefined || term === '') {
+				return
+			}
+			debouncedSearch(term).then((results) => {
+				this.autoCompleteContacts = uniqBy('id')(this.autoCompleteContacts.concat(results))
+			})
+		},
 	},
 }
 </script>
@@ -99,4 +220,60 @@ export default {
 .user-bubble-email {
 	margin: 10px;
 }
+
+.contact-popover {
+	display: inline-block;
+}
+.contact-wrapper {
+	padding:10px;
+	min-width: 300px;
+
+	a {
+		opacity: 0.7;
+	}
+	a:hover {
+		opacity: 1;
+	}
+}
+.contact-input-wrapper {
+	margin-top: 10px;
+    margin-bottom: 10px;
+	input,
+	.multiselect {
+		width: 100%;
+	}
+}
+.icon-user,
+.icon-reply,
+.icon-checkmark,
+.icon-close,
+.icon-add {
+	height: 44px;
+	min-width: 44px;
+	margin: 0;
+	padding: 9px 18px 10px 32px;
+}
+@media only screen and (min-width: 600px) {
+	.icon-user,
+	.icon-reply,
+	.icon-checkmark,
+	.icon-close,
+	.icon-add {
+		background-position: 12px center;
+	}
+}
+.icon-add {
+	display: revert;
+    vertical-align: revert;
+}
+.contact-existing {
+	margin-bottom: 10px;
+	font-size: small;
+	.icon-details {
+		padding-left: 34px;
+		background-position: 10px center;
+		text-align: left;
+	}
+}
+
 </style>
diff --git a/src/service/ContactIntegrationService.js b/src/service/ContactIntegrationService.js
new file mode 100644
index 0000000000..fdd43f3a6f
--- /dev/null
+++ b/src/service/ContactIntegrationService.js
@@ -0,0 +1,51 @@
+/*
+ * @copyright 2021 Kristian Lebold <kristian@lebold.info>
+ *
+ * @author 2021 Kristian Lebold <kristian@lebold.info>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+import Axios from '@nextcloud/axios'
+import { generateUrl } from '@nextcloud/router'
+
+export const findMatches = (mail) => {
+	const url = generateUrl('/apps/mail/api/contactIntegration/match/{mail}', {
+		mail,
+	})
+
+	return Axios.get(url).then((resp) => resp.data)
+}
+
+export const addToContact = (id, mailAddr) => {
+	const url = generateUrl('/apps/mail/api/contactIntegration/add')
+
+	return Axios.put(url, { uid: id, mail: mailAddr }).then((resp) => resp.data)
+}
+
+export const newContact = (name, mailAddr) => {
+	const url = generateUrl('/apps/mail/api/contactIntegration/new')
+
+	return Axios.put(url, { contactName: name, mail: mailAddr }).then((resp) => resp.data)
+}
+
+export const autoCompleteByName = (term) => {
+	const url = generateUrl('/apps/mail/api/contactIntegration/autoComplete/{term}', {
+		term,
+	})
+
+	return Axios.get(url).then((resp) => resp.data)
+}
diff --git a/tests/psalm-baseline.xml b/tests/psalm-baseline.xml
index d2e94c52bb..1cb8ae6f39 100644
--- a/tests/psalm-baseline.xml
+++ b/tests/psalm-baseline.xml
@@ -256,6 +256,11 @@
       <code>$predictedValidationLabel</code>
     </InvalidScalarArgument>
   </file>
+  <file src="lib/Service/ContactsIntegration.php">
+    <UndefinedDocblockClass occurrences="1">
+      <code>$this-&gt;contactsManager-&gt;getUserAddressBooks()</code>
+    </UndefinedDocblockClass>
+  </file>
   <file src="lib/Service/HtmlPurify/TransformURLScheme.php">
     <NullArgument occurrences="3">
       <code>null</code>