I have an AF solution which has many notifications configured.
When I test my Email devilry channel plugin configurations, and send a test mail to my email ID, it successfully sends the mail.
But when I try for some other email IDs or groups I get below error-
From Primary SMTP server: System.Net.Mail.SmtpFailedRecipientException: Mailbox unavailable. The server response was: 5.7.1 Unable to relay for "email ID name"
This is a new AF server on which I get this issue. We have another AF server and when I repeat the above from that server, the mail is sent successfully even though I have configured the same SMTP server name in the new server.
AF version is 2018R2 for the new one and 2017R2 in the older one.
Also I noted there was a difference in the extension of email IDs in success and failure cases. When email Ids are xyz.com it sends correctly and when it is xyz.com.sa it doesn't but I am not sure if this is the reason and how resolve it.
I have very less knowledge on SMTP server and its behaviors. Can anyone please advise?