Email bounce codes explained
What each bounce code means in plain words, whether it is a hard or soft bounce, and whose move it is. Have a bounce in front of you? Paste it into the bounce code lookup.
Microsoft 365 and Outlook bounce codes
| Code | Message | Bounce | Whose move |
|---|---|---|---|
550 5.4.1 | Recipient address rejected: Access denied | hard | Fix your list |
550 5.1.10 | Recipient not found | hard | Fix your list |
550 5.1.8 | Access denied, bad outbound sender | hard | Fix your sending setup |
550 5.1.90 | Daily limit for message recipients reached | hard | Wait and try again |
550 5.2.2 | Submission quota exceeded | hard | Wait and try again |
550 5.2.121 | Recipient's per hour message receive limit from specific sender exceeded | hard | Wait and try again |
550 5.2.122 | Recipient's per hour message receive limit exceeded | hard | Wait and try again |
550 5.7.23 | Rejected because of Sender Policy Framework violation | hard | Fix your sending setup |
530 5.7.57 | Client was not authenticated to send anonymous mail during MAIL FROM | hard | Fix your sending setup |
550 5.7.124 | Sender not in allowed-senders list | hard | Only the recipient side can fix it |
550 5.7.133 | Sender not authenticated for group | hard | Only the recipient side can fix it |
550 5.7.509 | Sending domain does not pass DMARC verification | hard | Fix your sending setup |
550 5.7.511 | Access denied, banned sender | hard | Fix your sending setup |
550 5.7.520 | Your organization does not allow external forwarding | hard | Only the recipient side can fix it |
550 5.7.606 | Access denied, banned sending IP | hard | Fix your sending setup |
Gmail and Google Workspace bounce codes
| Code | Message | Bounce | Whose move |
|---|---|---|---|
550 5.1.1 | The email account that you tried to reach does not exist | hard | Fix your list |
550 5.2.1 | The email account that you tried to reach is inactive | hard | Fix your list |
452 4.2.2 | The recipient's inbox is out of storage space | soft | Wait and try again |
421 4.7.0 | Temporarily rate limited: low reputation of the sending IP | soft | Fix your sending setup |
421 4.7.28 | Gmail has detected an unusual rate of email | soft | Fix your sending setup |
550 5.7.1 | This message is likely unsolicited mail | hard | Fix your sending setup |
550 5.7.26 | This email has been blocked because the sender is unauthenticated | hard | Fix your sending setup |
550 5.7.25 | The sending IP address doesn't have a PTR record | hard | Fix your sending setup |
550 5.4.5 | Daily user sending limit exceeded | hard | Wait and try again |
552 5.3.4 | Your message exceeded Google's message size limits | hard | Change the message |
How to read the last column
- Fix your list: the address or its domain is the problem. Remove or correct it.
- Fix your sending setup: the address is fine. Your domain, server or sending habits are the problem.
- Change the message: this one email is the problem, for example its size.
- Only the recipient side can fix it: a rule at the recipient's company blocks you.
- Wait and try again: a limit or a full mailbox. Nothing to repair.
The wording of each code comes from the lists that Google and Microsoft publish.
Free tools
- Bounce code lookup: paste any bounce message.
- Email list checker: find dead domains and typos before you send.
- SPF, DMARC and DKIM checker: for bounces about authentication.
- MX record checker: can a domain receive email at all?