Outgoing emails cannot be sent to external mailbox (firstname.lastname@example.org):
CONFIG_TEXT: MailEnable: Message could not be delivered to some recipients. The following recipient(s) could not be reached: Recipient: [SMTP:email@example.com] Reason: The message could not be delivered because the domain name (example.com) does not appear to be valid.
The following result is shown when trying to query mx record for example.com from local Plesk server:
C:\> nslookup -type=mx example.com
DNS request timed out.
timeout was 2 seconds.
DNS request timed out
But the request works fine from any other server:
# nslookup -type=mx example.com
example.com MX preference = 10, mail exchanger = mail.example.com
The following name servers serve mail.example.com, as it is shown when querying them from any other server:
# dig +trace mail.example.com
thirdpartydns.com rejects connection from certain servers, including Plesk server IP.
Contact thirdpartydns.com for assistance.