When any of our e-mail users try to send an e-mail to some specific domain (eg. asd@qwe.com.ty ), immediately get an undeliverable message with the following error.
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<mail.xyz.com.ab #5.5.0 smtp;550-Verification failed for <123@xyz.com.ab>>
I check both Dns (mx) and telnet tests. I also run test through
http://www.dnsreport.com/ . Results are fine.
We can send mail to this problematic address from hotmail or yahoo mail.
Internal e-mail users can send mails to all external address except the problematic domains.
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