What causes "inbox-not-found" in RocketChat/Rocket.Chat?

Confirm the inbox shows as active/connected in Administration > Email > Email Inboxes before testing

RocketChat/Rocket.Chat · error · Error

inbox-not-found

Error message

inbox-not-found

What it means

sendTestEmailToInbox looks up emailInboxRecord.email in the module-level `inboxes` Map, which only holds currently-active IMAP inbox connections registered by the incoming-email handling. 'inbox-not-found' (a plain Error, not Meteor.Error) means no live inbox is registered under that exact email address — the inbox worker is not running, not connected, or the record's email does not match the key the inbox registered under.

Source

Thrown at apps/meteor/server/features/EmailInbox/EmailInbox_Outgoing.ts:332

					type: 'mrkdwn',
					text: `> ---\n${replyToMessage.msg.replace(/^/gm, '> ')}`,
				},
			},
		];

		delete message.urls;

		return message;
	},
	callbacks.priority.LOW,
	'ReplyEmail',
);

export async function sendTestEmailToInbox(emailInboxRecord: IEmailInbox, user: IUser): Promise<void> {
	const inbox = inboxes.get(emailInboxRecord.email);

	if (!inbox) {
		throw new Error('inbox-not-found');
	}

	const address = user.emails?.find((email) => email.verified)?.address;

	if (!address) {
		throw new Error('user-without-verified-email');
	}

	void sendEmail(inbox, {
		to: address,
		subject: 'Test of inbox configuration',
		text: 'Test of inbox configuration successful',
	});
}

View on GitHub (pinned to b2c16d5842)

Solutions

Confirm the inbox shows as active/connected in Administration > Email > Email Inboxes before testing
Restart the server (or trigger the inbox worker) so the inbox registers in the map
Make sure emailInboxRecord.email exactly matches the address the inbox was registered with
On multi-instance setups, route the test to the instance holding the inbox connection

Defensive patterns

Strategy: try-catch

Try / catch

try {
  await sendTestEmailToInbox(inboxRecord, user);
} catch (e) {
  if (e instanceof Error && e.message === 'inbox-not-found') {
    // tell the admin the inbox is not active; suggest restart / checking IMAP status
  }
}

Prevention

Only expose the 'send test email' action when the inbox reports an active connection
After editing an inbox record, restart/re-register the inbox before testing
On multi-instance deployments, remember the inboxes map is per-process — route accordingly

When it happens

Trigger: Sending the test email right after server start before the IMAP inbox connected; the inbox record's email was edited without re-registering; IMAP connection failed at startup so the inbox never entered the map; calling on an instance whose process-local map does not hold the connection.

Common situations: Admin edits an inbox and immediately clicks 'send test email'; multi-instance deployments where the request lands on a node without the inbox worker; IMAP host temporarily down at boot so registration never happened.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

AI-assisted analysis of RocketChat/Rocket.Chat@b2c16d5842 (2026-08-18). Data as JSON: /api/errors/0288ac8bf0fb74fd. Report an issue: GitHub.