Gmail and Google Workspace · permanent error
550 5.7.1: IP not authorized to send directly
Gmail will not accept mail sent straight from your IP, typically a home or dynamic address, and asks you to send through your provider's mail server.
- Gmail
- Provider
- Permanent (5xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 550 5.7.1
- Provider
- Gmail and Google Workspace
- Temporary or permanent
- PermanentRefused for good: the message comes back to the sender, and resending it gets the same answer.
- Who has to act
- The sender. The fix is on the sending side: your domain, your server or your list.
- What the server says
550 5.7.1 The IP you're using to send email is not authorized to send email directly…
What it means
Gmail refuses direct delivery from some IP addresses, typically residential, dynamic or other end-user ranges that blocklists often flag, because infected home computers send so much spam from them. Your server, or a device on such a network, tried to deliver straight to Gmail's servers. The reply gives the fix itself: use the SMTP relay at your service provider instead. Google links it to a help article named after the error.
Common causes
- A mail server running on a home or business connection with a dynamic IP.
- A device or application that delivers directly to Gmail instead of through a mail server.
- An IP range listed as end-user or dynamic space.
How to fix it
- 01Send through your ISP's or email provider's SMTP server, as a smart host, instead of directly.
- 02Or use an authenticated submission service, such as your mailbox provider or a sending service.
- 03If you need to run your own mail server, host it on an IP meant for mail, with a PTR record and authentication.
- 04Check whether your IP appears on a blocklist of dynamic or end-user ranges.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
- Gmail SMTP errors and codes (Google Workspace Admin Help)knowledge.workspace.google.com
Related codes
- 550 5.7.1Blocked for low IP reputation.Gmail permanently rejected the message because the IP it came from has a very low reputation with Gmail.
- 550Mailbox unavailable.The receiving server permanently refused the message for this recipient: the mailbox does not exist, cannot be reached, or the server rejected the message by policy.
- 5.7.1Delivery not authorised.The receiving server refuses the message because this sender is not allowed to send to this recipient, as a result of filtering by host or by recipient.
5.7.1 at other providers
- 550 5.7.1Not authorized to send to this recipient.You do not have permission to send to this recipient, typically a group restricted to certain senders or a recipient protected by a mail flow rule.
- 550 5.7.1Public folder does not accept external mail.An external sender wrote to a mail-enabled public folder in Microsoft 365, which by default accepts mail only from authenticated senders.
- 550 5.7.1Sending IP blocked by Proofpoint Dynamic Reputation.Proofpoint’s IP reputation system has your sending IP on its block list because it has seen spam or viruses from it, so Proofpoint customers refuse your mail.
- 550 5.7.1SPF check failed.The recipient’s Cisco Secure Email gateway checked SPF, found your server not authorised for the sender domain, and its policy rejects that result.
- 550 5.7.1Rejected under your domain’s DMARC policy.Your message failed DMARC, your domain’s DMARC record asks receivers to reject such mail, and the recipient’s Cisco gateway did so.
- 550 5.7.1DMARC verification failed permanently.The Cisco gateway hit a permanent failure while verifying DMARC for your message, and the recipient’s policy rejects such mail. Cisco does not say what produces that failure.
Further reading
All 108 Gmail codesEvery code in the wikiPaste your own bounce