Gmail and Google Workspace · permanent error
550 5.7.1: invalid domain in the From header
Gmail rejected the message because the domain in its From address is not written in a form that RFC 5322 allows.
- 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 …because the From: header has a non-compliant domain name.
What it means
The domain part of the From address does not comply with RFC 5322. Gmail is checking how the domain is written here; whether it exists in DNS is a separate question. Typical faults are a space, a doubled or trailing dot, brackets or quotes, or raw non-ASCII characters where the punycode form belongs. The fix is to send from an address on a correctly written domain, which in practice means checking the configuration of the sending software.
Common causes
- A typo in the configured sender domain, such as a doubled or trailing dot.
- Spaces or other characters that are not allowed in a domain.
- An internationalized domain written in raw Unicode instead of its punycode form.
How to fix it
- 01Check the From address exactly as the software sends it.
- 02Correct the domain in the settings of the sending application or device.
- 03Write internationalized domains in their punycode (xn--) form.
- 04Resend once the address is valid.
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
- Email sender guidelines (Gmail Help)support.google.com
Related codes
- 550 5.7.1Missing or invalid From header.Gmail rejected the message because it has no From header, or the From header does not contain a valid email address.
- 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.
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