temporarily rejected RCPT <firstname.lastname@example.org>: lowest numbered MX record points to local host
The reason for the error message is the domain “domainname.tld” is missing from the /etc/localdomains file of your server. The difference between the /etc/localdomains and /etc/remotedomains files is that, they decide whether the email has to be delivered locally OR to a remote server respectively and is checked by the exim mail server.
To fix the issue, edit the file:
# vim /etc/localdomains
and place the domain name entry there. There is no need to restart the ‘exim’ s