>>> I'm looking for a way, in sendmail, to set access rule, saying:
>>>
>>> Accept messages for domain.com only from this IP address.
>>>
>>> I did some research yesterday, but could only find a way to restrict
>>> by IP for all domains managed by sendmail.
<snip>
>> Add rules to check sending host ip (client_addr) against domain. Put
>> the four missing lines in your Local_check_rcpt ruleset. You cannot
>> just copy and paste from this mail. Put a tab/tabs between the $: and
>> $#error and the > character of each line
>
> Probably easier, update /etc/hosts.{allow,deny} and/or update your
> firewall to block the port from undesirables.
How, may I ask, do you suggest providing the logic needed to
intelligently block connections as necessary?
I don't see what is so hard about adding a few lines to sendmail.cf and
making sure they are added properly and here the only requirement is
that there is at least one tab between the LHS and RHS of the ruleset
lines. Or maybe you did not read what the OP wanted to achieve at the top.