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'550 5.7.1 Unable to relay' Reports When Sending External Emails by Relay SMTP Server (Doc ID 1910507.1)

Last updated on MAY 17, 2021

Applies to:

Linux OS - Version Oracle Linux 5.10 and later
Oracle Cloud Infrastructure - Version N/A and later
Information in this document applies to any platform.


There are two relay servers configured for the sendmail server.

When sending email to external email address by relay smtp server, for example, to, not all the mails are received.

For example, only 4 emails can be received when sending 5 emails. And from telnet test result, relay server response with information '550 5.7.1 Unable to relay'.


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