I know the sender address verification in Postfix is a good thing. However, I would like to disable this check for one certain domain from which I get mails but which does not exist in DNS. How can I do that?
How to disable "Sender address rejected:Domain not found" for a single Domain in Postfix
Have a look at: http://www.kutukupret.com/2009/12/28/postfix-selective-sender-addresss-verification/
The idea is to create an smtpd restriction class which does not verify the sender address and use the access map so that only the domain you don't want to check matches that class.
Unfortunately the link you posted does not work (at least for me and at this time). Could you please provide more details?– simlevSep 19, 2019 at 7:10
Basically there are 8 restriction access lists that can apply when receiving mail. See https://www.postfix.org/SMTPD_ACCESS_README.html .
For each one which has an entry, you need to have a permit rule before any others that which allows the ip address you want whitelisted. The easy one to use is to add the ip to whitelist to the mynetworks setting and then add the permit_mynetworks rule at the start of each restriction.
All of these restrictions are empty by default, except for smtpd_relay_restrictions, which has a permit_mynetworks as the first rule. So if there are not other restrictions in place, one can simply add the address to the mynetworks setting and that should whitelist it.
One can also do this by adding a map as described for restriction in question, such as check_helo_access for the smtpd_helo_restrictions . This solution is perhaps a bit cleaner by not including outside ip in one's mynetworks setting.