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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?

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up vote 10 down vote accepted

I added the following in

define(`confDOMAIN_NAME', `')dnl

and then:

m4 >
service sendmail restart

I also verified that this worked with the email verifier service at ( Neat service, you send it an email and it replies to the from header with information about your SPF, Domain Keys, etc...

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Word of caution (perhaps common sense but I'll mention it anyway). The value for confDOMAIN_NAME should NOT be an email domain. Setting it to that will cause sendmail to reject messages because it thinks the mailboxes are (or should be) local. – Mike B Jul 7 at 17:29

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.


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define(confSMTP_LOGIN_MSG',$j; $b')dnl

Also configure /etc/hosts like below server server server server

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