nextcloud · hamza221 · May 7, 2026
@@ -11,6 +11,7 @@
 
 use OCA\Mail\Contracts\IMailManager;
 use OCA\Mail\Db\Message;
+use OCA\Mail\Db\MessageTags;
 use OCA\Mail\Db\ThreadMapper;
 use OCA\Mail\Exception\ClientException;
 use OCA\Mail\Service\AccountService;
@@ -102,6 +103,7 @@ public function run($argument): void {
 			$message,
 			$tag,
 			true,
+			MessageTags::TYPE_CLASSIFIER,
 		);
 	}
 }
@@ -14,6 +14,7 @@
 use OCA\Mail\Attachment;
 use OCA\Mail\Db\Mailbox;
 use OCA\Mail\Db\Message;
+use OCA\Mail\Db\MessageTags;
 use OCA\Mail\Db\Tag;
 use OCA\Mail\Exception\ClientException;
 use OCA\Mail\Exception\ServiceException;
@@ -183,11 +184,14 @@ public function flagMessage(Account $account, string $mailbox, int $uid, string
 	 * @param Message $message
 	 * @param Tag $tag
 	 * @param bool $value
+	 * @param string $type Source of the tag, one of MessageTags::TYPE_USER (default)
+	 *                    or MessageTags::TYPE_CLASSIFIER. Used so the importance
+	 *                    classifier does not train on its own predictions.
 	 *
 	 * @throws ClientException
 	 * @throws ServiceException
 	 */
-	public function tagMessage(Account $account, string $mailbox, Message $message, Tag $tag, bool $value): void;
+	public function tagMessage(Account $account, string $mailbox, Message $message, Tag $tag, bool $value, string $type = MessageTags::TYPE_USER): void;
 
 	/**
 	 * @param Account $account

@@ -18,13 +18,27 @@
  * @method void setImapMessageId(string $imapMessageId)
  * @method int getTagId()
  * @method void setTagId(int $tagId)
+ * @method string getType()
+ * @method void setType(string $type)
  */
 class MessageTags extends Entity implements JsonSerializable {
+	/**
+	 * Tag was applied by the user (manual interaction).
+	 */
+	public const TYPE_USER = 'user';
+
+	/**
+	 * Tag was applied by the automatic importance classifier.
+	 */
+	public const TYPE_CLASSIFIER = 'classifier';
+
 	protected $imapMessageId;
 	protected $tagId;
+	protected $type = self::TYPE_USER;
 
 	public function __construct() {
 		$this->addType('tagId', 'integer');
+		$this->addType('type', 'string');
 	}
 
 	#[\Override]
@@ -34,6 +48,7 @@ public function jsonSerialize() {
 			'id' => $this->getId(),
 			'imapMessageId' => $this->getImapMessageId(),
 			'tagId' => $this->getTagId(),
+			'type' => $this->getType(),
 		];
 	}
 }
@@ -76,7 +76,7 @@ public function getAllTagsForUser(string $userId): array {
 	 *
 	 * To tag (flag) a message on IMAP, @see \OCA\Mail\Service\MailManager::tagMessage
 	 */
-	public function tagMessage(Tag $tag, string $messageId, string $userId): void {
+	public function tagMessage(Tag $tag, string $messageId, string $userId, string $type = MessageTags::TYPE_USER): void {
 		try {
 			$tag = $this->getTagByImapLabel($tag->getImapLabel(), $userId);
 		} catch (DoesNotExistException $e) {
@@ -86,7 +86,8 @@ public function tagMessage(Tag $tag, string $messageId, string $userId): void {
 		$qb = $this->db->getQueryBuilder();
 		$qb->insert('mail_message_tags')
 			->setValue('imap_message_id', $qb->createNamedParameter($messageId))
-			->setValue('tag_id', $qb->createNamedParameter($tag->getId(), IQueryBuilder::PARAM_INT));
+			->setValue('tag_id', $qb->createNamedParameter($tag->getId(), IQueryBuilder::PARAM_INT))
+			->setValue('type', $qb->createNamedParameter($type));
 		$qb->executeStatement();
 	}
 
@@ -143,6 +144,44 @@ public function getAllTagsForMessages(array $messages, string $userId): array {
 		return $tags;
 	}
 
+	/**
+	 * Return the IMAP message IDs of messages whose given tag was applied by
+	 * the automatic classifier (rather than the user). Useful for excluding
+	 * classifier-applied labels from the importance classifier's training
+	 * set so it does not reinforce its own predictions.
+	 *
+	 * @param Message[] $messages
+	 * @return string[]
+	 */
+	public function getClassifierTaggedMessageIds(array $messages, string $userId, string $imapLabel): array {
+		if ($messages === []) {
+			return [];
+		}
+		$ids = array_map(static fn (Message $message) => $message->getMessageId(), $messages);
+
+		$qb = $this->db->getQueryBuilder();
+		$query = $qb->selectDistinct('mt.imap_message_id')
+			->from($this->getTableName(), 't')
+			->join('t', 'mail_message_tags', 'mt', $qb->expr()->eq('t.id', 'mt.tag_id', IQueryBuilder::PARAM_INT))
+			->where(
+				$qb->expr()->in('mt.imap_message_id', $qb->createParameter('ids'), IQueryBuilder::PARAM_STR_ARRAY),
+				$qb->expr()->eq('t.user_id', $qb->createNamedParameter($userId, IQueryBuilder::PARAM_STR)),
+				$qb->expr()->eq('t.imap_label', $qb->createNamedParameter($imapLabel, IQueryBuilder::PARAM_STR)),
+				$qb->expr()->eq('mt.type', $qb->createNamedParameter(MessageTags::TYPE_CLASSIFIER, IQueryBuilder::PARAM_STR)),
+			);
+
+		$messageIds = [];
+		foreach (array_chunk($ids, 1000) as $chunk) {
+			$query->setParameter('ids', $chunk, IQueryBuilder::PARAM_STR_ARRAY);
+			$result = $query->executeQuery();
+			while (($row = $result->fetch()) !== false) {
+				$messageIds[] = $row['imap_message_id'];
+			}
+			$result->closeCursor();
+		}
+		return $messageIds;
+	}
+
 	/**
 	 * @param Message[] $messages
 	 * @param string $userId

@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Mail\Migration;
+
+use Closure;
+use OCA\Mail\Db\MessageTags;
+use OCP\DB\ISchemaWrapper;
+use OCP\DB\Types;
+use OCP\Migration\Attributes\AddColumn;
+use OCP\Migration\Attributes\ColumnType;
+use OCP\Migration\IOutput;
+use OCP\Migration\SimpleMigrationStep;
+use Override;
+
+/**
+ * Tracks whether a message tag was applied by the user or by the
+ * automatic importance classifier. Existing rows are preserved as
+ * user-applied so they remain valid ground truth for training.
+ *
+ * @psalm-api
+ */
+#[AddColumn(
+	table: 'mail_message_tags',
+	name: 'type',
+	type: ColumnType::STRING,
+	description: 'Source of the tag: user vs classifier',
+)]
+class Version5900Date20260507120000 extends SimpleMigrationStep {
+
+	/**
+	 * @param Closure(): ISchemaWrapper $schemaClosure
+	 */
+	#[Override]
+	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
+		$schema = $schemaClosure();
+
+		if (!$schema->hasTable('mail_message_tags')) {
+			return null;
+		}
+
+		$table = $schema->getTable('mail_message_tags');
+		if (!$table->hasColumn('type')) {
+			$table->addColumn('type', Types::STRING, [
+				'notnull' => true,
+				'length' => 16,
+				'default' => MessageTags::TYPE_USER,
+			]);
+		}
+
+		return $schema;
+	}
+}
@@ -16,6 +16,8 @@
 use OCA\Mail\Db\MailboxMapper;
 use OCA\Mail\Db\Message;
 use OCA\Mail\Db\MessageMapper;
+use OCA\Mail\Db\Tag;
+use OCA\Mail\Db\TagMapper;
 use OCA\Mail\Exception\ClassifierTrainingException;
 use OCA\Mail\Exception\ServiceException;
 use OCA\Mail\Model\Classifier;
@@ -109,18 +111,22 @@ class ImportanceClassifier {
 
 	private ContainerInterface $container;
 
+	private TagMapper $tagMapper;
+
 	public function __construct(MailboxMapper $mailboxMapper,
 		MessageMapper $messageMapper,
 		PersistenceService $persistenceService,
 		PerformanceLogger $performanceLogger,
 		ImportanceRulesClassifier $rulesClassifier,
-		ContainerInterface $container) {
+		ContainerInterface $container,
+		TagMapper $tagMapper) {
 		$this->mailboxMapper = $mailboxMapper;
 		$this->messageMapper = $messageMapper;
 		$this->persistenceService = $persistenceService;
 		$this->performanceLogger = $performanceLogger;
 		$this->rulesClassifier = $rulesClassifier;
 		$this->container = $container;
+		$this->tagMapper = $tagMapper;
 	}
 
 	private static function createDefaultEstimator(): KNearestNeighbors {
@@ -180,10 +186,28 @@ public function buildDataSet(
 			$this->messageMapper->findLatestMessages($account->getUserId(), $mailboxIds, self::MAX_TRAINING_SET_SIZE),
 			[$this, 'filterMessageHasSenderEmail']
 		);
+
+		// Drop messages whose importance flag was set by the classifier itself.
+		// We have no ground truth for these, so including them would let the
+		// classifier reinforce its own predictions over time.
+		$classifierTaggedIds = array_flip($this->tagMapper->getClassifierTaggedMessageIds(
+			$messages,
+			$account->getUserId(),
+			Tag::LABEL_IMPORTANT,
+		));
+		$autoTaggedDropped = 0;
+		$messages = array_filter($messages, static function (Message $message) use ($classifierTaggedIds, &$autoTaggedDropped) {
+			if (isset($classifierTaggedIds[$message->getMessageId()])) {
+				$autoTaggedDropped++;
+				return false;
+			}
+			return true;
+		});
+
 		$importantMessages = array_filter($messages, static fn (Message $message) => $message->getFlagImportant() === true);
 		$nMessages = count($messages);
 		$nImportant = count($importantMessages);
-		$logger->debug("found $nMessages messages of which $nImportant are important");
+		$logger->debug("found $nMessages messages of which $nImportant are important (dropped $autoTaggedDropped classifier-tagged messages)");
 		if (count($importantMessages) < self::COLD_START_THRESHOLD) {
 			$logger->info('not enough messages to train a classifier');
 			return null;

@@ -14,6 +14,7 @@
 use OCA\Mail\Contracts\IMailManager;
 use OCA\Mail\Db\Mailbox;
 use OCA\Mail\Db\Message;
+use OCA\Mail\Db\MessageTags;
 use OCA\Mail\Db\Tag;
 use OCA\Mail\Db\TagMapper;
 use OCA\Mail\Exception\ClientException;
@@ -89,7 +90,7 @@ public function classifyNewMessages(
 				if ($prediction) {
 					$message->setFlagImportant(true);
 					$this->mailManager->flagMessage($account, $mailbox->getName(), $message->getUid(), Tag::LABEL_IMPORTANT, true);
-					$this->mailManager->tagMessage($account, $mailbox->getName(), $message, $importantTag, true);
+					$this->mailManager->tagMessage($account, $mailbox->getName(), $message, $importantTag, true, MessageTags::TYPE_CLASSIFIER);
 				}
 			}
 		} catch (ServiceException $e) {

@@ -21,6 +21,7 @@
 use OCA\Mail\Db\MailboxMapper;
 use OCA\Mail\Db\Message;
 use OCA\Mail\Db\MessageMapper as DbMessageMapper;
+use OCA\Mail\Db\MessageTags;
 use OCA\Mail\Db\MessageTagsMapper;
 use OCA\Mail\Db\Tag;
 use OCA\Mail\Db\TagMapper;
@@ -493,7 +494,7 @@ public function flagMessage(Account $account, string $mailbox, int $uid, string
 	 * @throws ClientException
 	 * @throws ServiceException
 	 */
-	public function tagMessagesWithClient(Horde_Imap_Client_Socket $client, Account $account, Mailbox $mailbox, array $messages, Tag $tag, bool $value):void {
+	public function tagMessagesWithClient(Horde_Imap_Client_Socket $client, Account $account, Mailbox $mailbox, array $messages, Tag $tag, bool $value, string $type = MessageTags::TYPE_USER):void {
 		if ($this->isPermflagsEnabled($client, $account, $mailbox->getName()) === true) {
 			$messageIds = array_map(static fn (Message $message) => $message->getUid(), $messages);
 			try {
@@ -514,7 +515,7 @@ public function tagMessagesWithClient(Horde_Imap_Client_Socket $client, Account
 
 		if ($value) {
 			foreach ($messages as $message) {
-				$this->tagMapper->tagMessage($tag, $message->getMessageId(), $account->getUserId());
+				$this->tagMapper->tagMessage($tag, $message->getMessageId(), $account->getUserId(), $type);
 			}
 		} else {
 			foreach ($messages as $message) {
@@ -540,15 +541,15 @@ public function tagMessagesWithClient(Horde_Imap_Client_Socket $client, Account
 	 * @link https://github.com/nextcloud/mail/issues/25
 	 */
 	#[\Override]
-	public function tagMessage(Account $account, string $mailbox, Message $message, Tag $tag, bool $value): void {
+	public function tagMessage(Account $account, string $mailbox, Message $message, Tag $tag, bool $value, string $type = MessageTags::TYPE_USER): void {
 		try {
 			$mb = $this->mailboxMapper->find($account, $mailbox);
 		} catch (DoesNotExistException $e) {
 			throw new ClientException("Mailbox $mailbox does not exist", 0, $e);
 		}
 		$client = $this->imapClientFactory->getClient($account);
 		try {
-			$this->tagMessagesWithClient($client, $account, $mb, [$message], $tag, $value);
+			$this->tagMessagesWithClient($client, $account, $mb, [$message], $tag, $value, $type);
 		} finally {
 			$client->logout();
 		}

@@ -16,6 +16,7 @@
 use OCA\Mail\Db\MailAccount;
 use OCA\Mail\Db\Mailbox;
 use OCA\Mail\Db\Message;
+use OCA\Mail\Db\MessageTags;
 use OCA\Mail\Db\Tag;
 use OCA\Mail\Db\ThreadMapper;
 use OCA\Mail\Service\AccountService;
@@ -115,7 +116,7 @@ public function testRun(): void {
 			->willReturn($tag);
 		$this->mailManager->expects(self::once())
 			->method('tagMessage')
-			->with($account, 'sent', $message, $tag, true);
+			->with($account, 'sent', $message, $tag, true, MessageTags::TYPE_CLASSIFIER);
 
 		$this->job->run($argument);
 	}
@@ -248,7 +249,7 @@ public function testRunMultipleMessages(): void {
 			->willReturn($tag);
 		$this->mailManager->expects(self::once())
 			->method('tagMessage')
-			->with($account, 'sent', $message, $tag, true);
+			->with($account, 'sent', $message, $tag, true, MessageTags::TYPE_CLASSIFIER);
 
 		$this->job->run($argument);
 	}
@@ -302,7 +303,7 @@ public function testRunCreateTag(): void {
 			->willReturn($tag);
 		$this->mailManager->expects(self::once())
 			->method('tagMessage')
-			->with($account, 'sent', $message, $tag, true);
+			->with($account, 'sent', $message, $tag, true, MessageTags::TYPE_CLASSIFIER);
 
 		$this->job->run($argument);
 	}

@@ -18,6 +18,7 @@
 use OCA\Mail\Db\MailboxMapper;
 use OCA\Mail\Db\Message;
 use OCA\Mail\Db\MessageMapper as DbMessageMapper;
+use OCA\Mail\Db\MessageTags;
 use OCA\Mail\Db\MessageTagsMapper;
 use OCA\Mail\Db\Tag;
 use OCA\Mail\Db\TagMapper;
@@ -450,6 +451,9 @@ public function testTagMessage(): void {
 		$account->expects($this->once())
 			->method('getUserId')
 			->willReturn('test');
+		$this->tagMapper->expects($this->once())
+			->method('tagMessage')
+			->with($tag, $message->getMessageId(), 'test', MessageTags::TYPE_USER);
 		$this->manager->tagMessage($account, 'INBOX', $message, $tag, true);
 	}