Error codes

550 5.7.1 The IP you're using to send email is not authorized to send email directly to our servers. Use the SMTP relay at your service provider instead.

Gmail blocked the message because the sending IP is not allowed to deliver straight to Gmail. It tells you to use the SMTP relay at the service provider.

550 5.7.1 is used for many other Gmail blocks. This page is only the direct-to-Gmail IP row on the SMTP error list, last updated 18 September 2026 UTC.