Troubleshoot MTA issues

Troubleshooting : Troubleshoot MTA issues

Problem

SMTP clients receive the message 550 5.7.1 Relay access denied.

Solution

This indicates rejection due to lack of relay permission.

• For incoming connections, relay will be allowed automatically unless explicitly rejected through the access control list (see “Configuring access control rules”).

• For outgoing connections, relay will be allowed only if explicitly granted by authentication (see “Controlling email based on IP addresses”) or by the access control list (see “Configuring access control rules”). If authentication is required, verify that the SMTP client is configured to authenticate.

If you receive a 5.7.1 error message that does not mention relay access, and sender reputation or endpoint reputation is enabled, verify that the SMTP client has not exceeded the reputation score threshold for rejection.