When sending mail to a mailbox, it gets bounced with a message saying that no such mailbox exists.
The mail is bounced back with one of the following errors:
Hi. This is the qmail-send program at SERVER. I'm afraid I wasn't able to deliver your message to the following addresses. This is a permanent error; I've given up. Sorry it didn't work out This address no longer accepts mail. Sorry, no mailbox here by that name. (#5.1.1) 550 Requested action not taken: mailbox unavailable Givingup. User not known Giving up. Sorry your message to firstname.lastname@example.org cannot be delivered. This account has been disabled or discontinued.
Mail recipient mailbox does not exist.
Check the MX record of the domain you are sending a message to:
c:\Nmap>nslookup -q=mx example.com Non-authoritative answer: example.com MX preference = 10, mail exchanger = mail.example.com mail.example.com internet address = 18.104.22.168
# dig mx +short example.com mail.example.com # dig +short mail.example.com 22.214.171.124
If the MX record resolves into a different server, and this domain is not present on the Plesk Automation (PA) mail node, ask administrator of the server if the mailbox exists.
If the error occurs while sending mail to the PA mail node, make sure that the mail address exists and that mail service for the domain is enabled.
Also, check that the MX (A) record of the destination domain resolves into appropriate server.
If the MX record resolves into a different server, but the domain is hosted on the PA mail node, correct the MX record in DNS settings of the domain.
Disable mail service under Customer Control Panel > Mail > Change Settings > Activate mail service on domain.