Hi all,

I know that Sendmail 8.12.11 has built-in rulesets that kick in by
default. In particular, check_relay should activate every time an
(e)SMTP connection is made to the mail server.

My issue currently is that check_relay fires in some situations and not
in others. Cases where it doesn't, the relay server is allowed to
carry out a dictionary attack. I have specifically flagged mail from
these relays to be DISCARDed within /etc/mail/access. I thought
check_relay was the first ruleset to be called and if a match is found
in access.db access is denied. If this is not correct and I'm mistaken
in my logic please educate me

IMO check_rcpt or check_mail should never be called if a relay is
explicitly denied SMTP access within /etc/mail/access. Below is an
example access.db file resembling my setup.

# Repeated offenders
asahi-net.or.jp 550 Your domain/host is not allowed to
relay to our network
brasiltelecom.net.br DISCARD

# 10/09/2006
221.202.220.201 550 Your domain/host is not allowed to
relay to our network

# 11/09/2006
124.121.18.37 550 Your domain/host is not allowed to
relay to our network

# Allow relay from local network
localhost.localdomain RELAY
localhost RELAY
127.0.0.1 RELAY
myserver.domain RELAY
subnet.1 RELAY
subnet.2 RELAY

# Local Users
To:user1@domain RELAY
To:user2@domain RELAY
To:user1@domain2 RELAY
To:user2@domain2 RELAY

# Catch all other users
To:domain error:5.1.1:"550 User unknown"
To:domain2 error:5.1.1:"550 User unknown"

The dated rejection lists are only kept for 4 days and are temporary so
as to not affect genuine mailers. If further information is required I
will be more than happy to provide what's necessary.

Thanks all!