What is deferred emails and how to prevent it

[psytanium]

Hello,

I have 1 user hosted on the server, using webmail. He keep getting a bounce back message about deferred :

Domain name exceeded the max defers and failures per hour (5/5 100%) allowed. Message discarded.

I checked the "Mail Delivery Reports" in WHM, the domain name didn't send more than 30 email per day. What is wrong ? what type of emails are considered differed ?

Thanks

 

[cPRex]

Hey there! The number of messages sent overall isn't necessarily related to the issue, as long as you trigger the max number of defers per hour. 5 is the default value set in WHM >> Tweak Settings.

In your example, the domain could only send 5 emails and have this protection triggered, if they all failed or were marked as deferred. We have a great explanation of this here: What does the defer and failures (x/5) message really mean?

It would be best to check the /var/log/exim_mainlog file on the server to see if you can get more details on why the mail is failing or being marked as deferred. It's possible the recipient doesn't exist, or there is an IP reputation issue, but the only way to know for sure is the check that mail log.

 

[psytanium]

So a defer email means a mail sent and bounced back for any reason ? for example, the none delivery message "No such user" indicate a deferred email ?

 

[cPRex]

That's correct.