David wrote:
yes, but the spf record is not for helo checking, not sure if this
will cause any problem.
and also:
why not just use spf to check the mail from and use another protocol
to check the helo. If you have another txt register to show others how
should a certain domain name be used in helo/ehlo you could help others
filter a lot of junk. If you try to make your own rules to check
helo strings you will end either stoping legitimate mail or having
to accept junk messages (or having to filter them with other more
expensive rules).
Section 2.2.1 of the specification of SPF Classic
(http://spf.pobox.com/spf-draft-200406.txt) says:
When the return-path has no domain, a client MUST use the HELO domain
instead.
Roger