"Connection error" — what it means and how to fix it
A mailbox shows Connection error when its provider rejected the login or account; here is how to read the message and what fixes each one.
Where: Mailboxes → the Disconnected pill (hover it for the reason; Status filter: Disconnected); the full reason is also on the mailbox's page, in the "Mailbox … disconnected" row on the Notifications page, in the "Action needed: N mailboxes stopped working" email, and in the red banner at the top of every page
How to do it
- Open Mailboxes and filter Status → Disconnected, or click "Fix on Senders" in the red banner.
- Read the full error text: hover the Disconnected pill, open the mailbox (the red "Disconnected" line at the top and General → Connection), or see the "Mailbox … disconnected" row on the Notifications page or the "Action needed" email. If the mailbox was just imported, the reason also shows in the import dialog's Imported column.
- Apply the fix for that message (see the list below).
- If the fix involved a new password, re-import the mailbox with the new credentials (CSV). Otherwise use "Reconnect" (the row's ⋯ menu or the mailbox's page) — for a mailbox connected with Google or Microsoft sign-in it signs in again — or "Recheck Connections" above the list, and wait for the pill to turn Active. A paused mailbox stays Paused after a passing check — click Resume Sending when you're ready.
Good to know
- "SMTP rejected the credentials. For Gmail/Google Workspace you must use a 16-character App Password…" — the password is wrong or is the normal account password. Create an app password (Google Account → Security → 2-Step Verification → App passwords) for that exact account, paste it without spaces, and re-import.
- "SMTP rejected the credentials. Check the username and password." — for non-Google providers: wrong login, or (Microsoft 365) SMTP AUTH not enabled for the mailbox. Fix at the provider and re-import.
- "…the mail provider blocked this sign-in from the app's IP as a security challenge — the password is not the problem…" — Gmail's one-time challenge. Open the account in a browser (or visit accounts.google.com/DisplayUnlockCaptcha) to approve the sign-in, then Reconnect. Mailboxes connected with Google sign-in through Zapmail never hit this.
- "SMTP connection refused. The host or port is wrong…" / "SMTP host could not be resolved…" — fix the host/port with Bulk Edit → Connection (a Google or Outlook preset fills the right values) and the mailbox is re-verified automatically.
- "SMTP connection timed out after 15s, twice…" — a firewall or provider throttle. Wait a few minutes before changing anything; MailFleet re-checks this kind of error every 8 minutes by itself.
- "SMTP TLS certificate could not be validated…" — a private mail server with a self-signed certificate. Bulk Edit → Connection → "Self-Signed / Invalid Certificates" → "Allow (Private Mail Servers)".
- "Google revoked this mailbox's authorization … reconnect it" (Google sign-in mailboxes) — click Reconnect to sign in with Google again; a mailbox connected through Zapmail is reconnected from Zapmail.
- While a mailbox is in Error, campaigns keep sending from your other mailboxes — including follow-ups in conversations the broken mailbox started, which go out from another of your active senders rather than waiting.
- This email is sent to every member of the workspace whenever a mailbox disconnects; it cannot currently be switched off (the Settings → Notifications → Mailboxes switch does not affect it).
Questions people ask
Do I lose anything when a mailbox goes into Error?
No. Its leads stay enrolled and due; sends simply skip it until it is Active again. Replies to emails it already sent are still collected.