FREEBSD Outgoing Mail Issue - Dual Domain Extension (.com.com)

For a long time, over 6 years, my server was doing well. All moved along nicely without a hitch. Yet, when I tried to use VULTR.com's "snapshot" feature to create an identical server from this long-standing server. Meaning, exact same file system, layout and OS, but on a different IP. It would seem my original server, which has been up for so long, was changed in the process of creating a snapshot of it, or indeed forking it over unto a new server instance. Now. I have two .com.com on outgoing email messages from my long-standing server, as reported by spam checkers on the Internet. Now, instead of domainname.com on outgoing emails, my SPAMHAUS check shows my emails being sent from domainname.com.com (two .com). Question: Where can I look to see how I can mitigate or outright fix this two domain extension (.com.com) issue? I've since killed the new forked server, even if it was on an entirely different IP address. Yet, the issue hasn't abated. I've checked various settings, and even tried setting /etc/mail/mailertable to no avail. Any clues would be great. Thanks, guys! Glad to be back here, again, been a long time. Information from the system: # uname -a # hostname # cat /etc/rc.conf # cat /etc/mailer.conf | grep sendmail # ls /etc/mail/*.mc # cat /etc/mail/*.mc (in reality sendmail.mc is the most interesting one)