Mail from one server being rejected

[Dean_Collins]

Plesk v12.5.30_build1205150826.19 os_CentOS 7

This morning, one client suddenly began having his email rejected. His is apparently the only one this happens to. He's not blacklisted either on my server or on any block list that I can find.

The rejection/failure he receives looks like this:

Delivery has failed to these recipients or groups:

[email protected] (or any other address on the server)

A problem occurred during the delivery of this message to this e-mail address. Try sending this message again. If the problem continues, please contact your helpdesk.

The following organization rejected your message: mypleskserver.com.

Diagnostic information for administrators:

Generating server: variouslettersandnumbers.mail.protection.outlook.com

[email protected]
mypleskserver.com #<mypleskserver.com #5.0.350 smtp;550 5.0.350 Remote server returned an error -> 554 mail server permanently rejected message (#5.3.0)> #SMTP#

Original message headers:
[removed]

 

[Dean_Collins]

Sorry! I probably should have been clearer. The client is NOT a client on the Plesk server. His mail from a remote domain to my domain, which is on my Plesk server, is rejected. Everyone else can email me.

 

[PriyanA]

Most probably his email account/server has marked as spammed.

Do you have Spammassassin installed?

 

[Dean_Collins]

Yes. Spamassassin is installed. But the domain is whitelisted.

More info: I host the website for the domain mcwd.org. However, their mail is hosted elsewhere (Outlook Exchange). I have mail turned off for the domain.

 

[Dean_Collins]

I don't know specifically yet what it was, but it was on their side of things. If they ever tell me, I'll post it here.

Thanks!