[plug] controlling GNU mail sender address

[Gregory Orange]

Hi all,

Since I moved from a Mythbuntu 12.04 to a new Mythbuntu 14.04 machine,
mail hasn't worked quite the same. Sending mail with...

echo "some body" | mail -s "some subject" recipient at recipient.example.com

... used to work, with default sender address being user at mydomain.com.
It doesn't work on the new server, because default sender address is
user at machine.mydomain.com and upstream MX rightly complains that the
domain is invalid.

I can make it work with:
echo "some body" | mail -r "user at mydomain.com" -s "some subject"
recipient at recipient.example.com

I would like to make it work with configuration instead of a command
line argument. http://mailutils.org/manual/mailutils.html#SEC107 says
I can edit /etc/mail.rc or ~/.mailrc but I can't figure out what
settings to enter.

Can anyone here help me, or point me toward somewhere I can get help?

Thanks,
Greg.

-- 
Gregory Orange