If you do this you will block all bounces from sendmail machines. The
empty address is a special address that sendmail will (by default)
deliver but not bounce or forward. Thus a bounce message is converted
to an empty from: so if the return address is faulty, no mail loop is
formed.
Instead of adding a rule to the check_mail hook, you might comment out
the rules that allow delivery of an empty address. It's been awhile but
it is possible that there is a switch in the latest version that turns
it off for you. I seem to remember something about it.
Get the bat book and the latest sendmail. Use the
comp.protocols.sendmail newsgroup. Lots of knowledgeable help in those
resources.
-fg
> -----Original Message-----
> From: Randy Grimshaw [SMTP:rgrimsha @
mailbox .
syr .
edu]
> Sent: Monday, March 09, 1998 7:03
> To: Chris Brenton
> Cc: firewalls @
GreatCircle .
COM
> Subject: Re: Hiding reply addresses
>
>
> You can add the following rule to the *check_mail* hook in sendmail
> tab
> R$*<> $#error $@ 5.7.1 $: "551 You must provide a proper from
> address"
> ^
>
> This will require the sender to provide something as a mail from:
> value
> and then any content given will be checked by the regular tests that
> you
> provide. See sendmail.org for additional info about the hook.
>
> <><Randall Grimshaw, Network Programmer, Syracuse University,
> 315-443-5779
>
> On Fri, 6 Mar 1998, Chris Brenton wrote:
>
> > The blank return path bothered me. I've tested this off of a few
> mail systems
> > and was surprised to see that all of them would accept a blank "mail
> from:"
> > line. Are there any firewalls out there that would kick this message
> out by
> > default? Mail systems?
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