Error status=deferred refused to talk to me 554

Some of my users are getting an error status=deferred refused to talk to me 554 while sending emails. How to solve this.

Thanaks in advance

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Comments

This could be due to grey listing - have you enabled it in Virtualmin? Deferring email is an intentional strategy to block spammers, but should be invisible to users.

Hmm, where are you seeing those errors?

It doesn't appear that greylisting is enabled on your server, so that shouldn't be the cause.

But if you could let us know where you're seeing that error, and if there's any other messages associated with that error, that'd be helpful too.