From a6719b8db71802ee6818f87266558417e302d11f Mon Sep 17 00:00:00 2001
From: Bernhard Wittmann <bernhard.wittmann@n8n.io>
Date: Fri, 16 Oct 2026 13:10:25 +0000
Subject: [PATCH] fix(Email Trigger (IMAP) Node): Check the mailbox when the
 trigger activates (#41013)

---
 .../v2/EmailReadImapV2.node.test.ts           | 62 ++++++++++++++-----
 .../EmailReadImap/v2/EmailReadImapV2.node.ts  |  3 +-
 2 files changed, 47 insertions(+), 18 deletions(-)

diff --git a/packages/nodes-base/nodes/EmailReadImap/v2/EmailReadImapV2.node.test.ts b/packages/nodes-base/nodes/EmailReadImap/v2/EmailReadImapV2.node.test.ts
index bf12beaf6ca..03dd20e01fa 100644
--- a/packages/nodes-base/nodes/EmailReadImap/v2/EmailReadImapV2.node.test.ts
+++ b/packages/nodes-base/nodes/EmailReadImap/v2/EmailReadImapV2.node.test.ts
@@ -303,25 +303,53 @@ describe('EmailReadImapV2', () => {
 		});
 	});
 
-	describe('catching up after a gap', () => {
-		it('looks at the mailbox when it has processed mail before', async () => {
-			staticData.lastMessageUid = 42;
-			const connection = createConnection();
-			connectMock.mockResolvedValueOnce(connection);
+	describe('catching up on activation', () => {
+		// Mail that landed while the workflow was inactive sends no arrival event.
+		it.each([
+			{
+				case: 'mail processed before',
+				typeVersion: 2.1,
+				lastMessageUid: 42,
+				options: {},
+				criteria: ['UNSEEN', ['UID', '42:*']],
+			},
+			{
+				case: 'a first activation',
+				typeVersion: 2.1,
+				lastMessageUid: undefined,
+				options: {},
+				criteria: ['UNSEEN', ['SINCE', '13-Oct-2026']],
+			},
+			{
+				case: 'an untracked last message id',
+				typeVersion: 2.1,
+				lastMessageUid: 42,
+				options: { trackLastMessageId: false },
+				criteria: ['UNSEEN'],
+			},
+			{
+				case: 'version 2',
+				typeVersion: 2,
+				lastMessageUid: 42,
+				options: {},
+				criteria: ['UNSEEN'],
+			},
+		])(
+			'searches the mailbox after $case',
+			async ({ typeVersion, lastMessageUid, options, criteria }) => {
+				vi.setSystemTime(new Date('2026-10-13T12:00:00Z'));
+				triggerFunctions.getNode.mockReturnValue(mock<INode>({ typeVersion }));
+				staticData.lastMessageUid = lastMessageUid;
+				const connection = createConnection();
+				connectMock.mockResolvedValueOnce(connection);
 
-			await startTrigger();
+				await startTrigger(options);
+				expect(connection.catchUp).toHaveBeenCalledTimes(1);
+				await arrive(connection, 'unknown');
 
-			expect(connection.catchUp).toHaveBeenCalledTimes(1);
-		});
-
-		it('leaves the mailbox alone on a first activation', async () => {
-			const connection = createConnection();
-			connectMock.mockResolvedValueOnce(connection);
-
-			await startTrigger();
-
-			expect(connection.catchUp).not.toHaveBeenCalled();
-		});
+				expect(fetched).toHaveBeenCalledWith(expect.objectContaining({ searchCriteria: criteria }));
+			},
+		);
 	});
 
 	describe('credential test', () => {
diff --git a/packages/nodes-base/nodes/EmailReadImap/v2/EmailReadImapV2.node.ts b/packages/nodes-base/nodes/EmailReadImap/v2/EmailReadImapV2.node.ts
index ec0b33466d7..fc6475f969f 100644
--- a/packages/nodes-base/nodes/EmailReadImap/v2/EmailReadImapV2.node.ts
+++ b/packages/nodes-base/nodes/EmailReadImap/v2/EmailReadImapV2.node.ts
@@ -342,7 +342,8 @@ export class EmailReadImapV2 implements INodeType {
 
 		connection.onArrival(async ({ count }) => await fetchNewEmails(connection, count));
 
-		if (staticData.lastMessageUid !== undefined) connection.catchUp();
+		// Mail that landed while the trigger was inactive sends no arrival event.
+		connection.catchUp();
 
 		connection.onFlags((info) => {
 			this.logger.debug(`Email Read Imap:update ${info.seq}`, { uid: info.uid });