How do you specify the FQDN (Host and Domain Name) that a mail server presents itself as in HELO/EHLO when sending outgoing email with sendmail?
I added the following in sendmail.mc:
m4 sendmail.mc > sendmail.cf service sendmail restart
I also verified that this worked with the email verifier service at http://www.port25.com/domainkeys/ (firstname.lastname@example.org). Neat service, you send it an email and it replies to the from header with information about your SPF, Domain Keys, etc...
For completeness - one can also use
if one needs more absolute control (e.g. in a freeb-bsd jail it may be desirable to have the confDOMAIN_NAME and MASQUERADE_AS set very different than the HELO/EHLO names.
define(`confSMTP_LOGIN_MSG', `$j; $b')dnl
/etc/hosts file like below
xxx.xxx.xxx.xxx server server.yourdomain.com server 127.0.0.1 server server.yourdomain.com server