Re: tlug: Sendmail won't deliver from unrecognized host.

["Stephen J. Turnbull" <turnbull@example.com>]

>>>>> "Frank" == Frank Bennett <bennett@example.com> writes:

    Frank> Have a look in sendmail sources under cf/README, and search
    Frank> for "resolv".  There's a feature called
    Frank> "accept_unresolvable_addresses" or something like that
    Frank> which might loosen things up enough for things to work for
    Frank> you.

As well as improving RFC 1123 compliance which specifically prohibits
checking that kind of thing.

    Frank> The reason for insisting on resolution is to try to
    Frank> discourage spoofers and spammers, but the marginal loss of
    Frank> Internet discipline from loosening that up on a single
    Frank> machine is pretty small, so I wouldn't worry about it.

The protocols simply don't allow that to be an effective "discipline."
The only way for selection on sender address to work effectively is to
accept mail only from trusted partners.  But in that case you should
use a firewall (or good ol' tcp-wrappers) to deny or reject the TCP
connection from anyone else; why waste CPU and bus cycles firing up
sendmail?

I disabled that silliness immediately upon learning of it.  I get
almost all my spam relayed via trusted hosts anyway.  Content-based
filtering is much more effective.

And my system gets mail from a lot of places, not all of which can be
trusted to implement SMTP right, even in this day and age!

-- 
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Institute of Policy and Planning Sciences        Tel/fax: +1 (298) 53-5091
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