Filtering out "may be forged" connections

[Clark Smith]

Every so often I get connection requests to my sendmail server
that my server labels as "may be forged". Is there a way to configure
the /etc/mail/access file so that such connection requests are
immediately rejected?

[Andrzej Adam Filip]

Take a look at FEATURE(`anfi/rsdnsbl') [it is not supported by sendmail.org]
I would suggest you excluding a few "near by countries" from such strict checks.

http://groups.google.com/group/comp.mail.sendmail/browse_thread/thread/28bc896e5746cfde/4c19614405010236

[atlas...@gmail.com]

[Claus Aßmann]

> On Thursday, 26 April 2012 02:08:40 UTC+5:30, Clark Smith wrote:
> > Every so often I get connection requests to my sendmail server
> > that my server labels as "may be forged". Is there a way to configure
> > the /etc/mail/access file so that such connection requests are
> > immediately rejected?

No. See cf/README.

You can write your own custom ruleset (Local_check_*) and
check the value of {client_resolve} ($&{client_resolve}),
see doc/op/op.*

For example (test this first!):

SLocal_check_relay
R$* $: $&{client_resolve}
RTEMP $#error $@ 4.7.1 $: "450 Access temporarily denied. Cannot resolve PTR record for " $&{client_addr}
RFORGED $#error $@ 4.7.1 $: "450 Access temporarily denied. IP name possibly forged " $&{client_name}
RFAIL $#error $@ 4.7.1 $: "450 Access temporarily denied. IP name lookup failed " $&{client_name}