I did an apt-get update of a server "myserver.com" recently and now all emails sent from that server to firstname.lastname@example.org bounce with "user unknown". I believe that the server is trying to deliver to local users, but I am not sure why it changed to do this, or how to change it to send them correctly.
Any advice is welcomed! The messages are sent via the mail function in php.
Using Ubuntu 16
/etc/hostname is www-server.mydomain.com
127.0.0.1 localhost www.mydomain.com admin.mydomain.com 127.0.1.1 mydomain
If I use
sendmail on the commandline, I can send an email to email@example.com, or other email addresses, but I can no longer send to firstname.lastname@example.org. With
sendmail I don't know how to see what happens, but I have had users report emails sent to email@example.com from my php based website bouncing back to the user with the message "user unknown".
If I send an email to firstname.lastname@example.org from gmail, it works fine and I receive the email, so I know the problem is on this server
This all started happening after doing an apt-get upgrade (which had quite a few updates to do)
user@www-server:~# nslookup -query=mx mydomain.com Server: 94.199.n.n Address: 94.199.n.n#53 Non-authoritative answer: mydomain.com mail exchanger = 10 mail.mymailserver.com. Authoritative answers can be found from: mydomain.com nameserver = ns2.domainprovider.com. mydomain.com nameserver = ns.domainprovider.com. mail.mymailserver.com internet address = 94.199.x.x ns.domainprovider.com internet address = 212.67.y.y ns2.domainprovider.com internet address = 62.138.z.z
Note: IP Address of this server is not mentioned in the nslookup output