554 5.7.1 / 550 5.7.1: Relay access denied / Unable to relay

AnySMTP

The error usually looks like this:

554 5.7.1 <[email protected]>: Relay access denied

What it means

The server refused to pass your message on to another domain, because your app didn’t sign in (or isn’t allowed to relay).

Common causes

  • SMTP authentication is turned off in your app.
  • You are sending through a server that only accepts mail for its own domains (such as the recipient’s MX server, or the wrong SMTP host).

How to fix it

  1. Turn on SMTP authentication in your app, and use your provider’s submission server (usually port 587 or 465).
  2. Find the correct sending server with our settings finder.

Tools to help diagnose it

Email server settings finder

Find the IMAP, POP, and SMTP server names, ports and encryption settings for any email address

SMTP connection tester

Spin up a real SMTP test server and diagnose your email sending configuration in real time

Email server checker

Check any IMAP, POP or SMTP server’s encryption, certificate and supported sign-in methods

A free tool provided by Auth-Email

Auth-Email makes your Gmail, Outlook, or other OAuth 2.0 email account available to any IMAP, POP3, or SMTP email client — no app passwords or special configuration needed.

Read the docsTry Auth-Email →

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