Bounce codes · Permanent

550 5.2.1: Recipient account inactive or disabled

Gmail returns 550 5.2.1 when the recipient account is inactive, and also when the recipient is receiving mail too fast to accept more. The RFC meaning is "mailbox disabled, not accepting messages". For an inactive account, remove the address. For the rate variant, send to that address less often.

The exact messages

Gmail / Google Workspace

550 5.2.1 The email account that you tried to reach is inactive.

Gmail / Google Workspace

550 5.2.1 The user you are trying to contact is receiving email at a rate that prevents additional messages from being delivered.

Any mail server (RFC standard meaning)

5.2.1 Mailbox disabled, not accepting messages

Why it happens

The Google account was disabled or abandoned.
The recipient is being flooded with mail.

How to fix it

Inactive account: suppress the address.
Rate variant: space out mail to that recipient.

If you send cold email

Inactive-account bounces suggest a stale list. If several appear in one campaign, re-verify the whole list.

How WarmHawk handles it

A hard bounce marks that lead as bounced and stops its sequence, and every bounce counts toward the mailbox’s bounce-rate breaker: at 5% over at least 20 sends, WarmHawk pauses the mailbox before a stale list can damage the domain. How WarmHawk works →

Related bounce codes

Sources, checked 2026-09-29: Google Workspace: Gmail SMTP errors and codes · RFC 3463: Enhanced Mail System Status Codes. Have a different bounce? Paste it into the decoder →

Questions

5.2.1 questions

What does 5.2.1 mean?+

Is 5.2.1 a temporary or permanent error?+

Permanent. The message will not be retried, and sending it again unchanged will fail the same way until the cause is fixed.

How do I fix 5.2.1?+

Inactive account: suppress the address. Rate variant: space out mail to that recipient.