How to Specify outgoing HELO with sendmail?

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:

define(`confDOMAIN_NAME', `mail.foo.com')dnl

and then:

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/ ([email protected]). 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

define(confHELO_NAME,`something.not.the.same.as.the.domain.name')

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.

Dw.