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...