Fazzina, Angelo: > Hi, I have a domain that has MX point to O365 and then O365 relays > mail to Postfix server. Currently, Postfix does a lookup in a > MySql table to know where to relay the email to, AFA next hop. If > not found in table Postfix looks up MX and relays the email.
Postfix should first verfy that the recipient exists, before accepting the mail. Perhaps you can use the MySQL table with relay_recipient_maps. For more info on inbound recipient validation: http://www.postfix.org/STANDARD_CONFIGURATION_README.html http://www.postfix.org/ADDRESS_VERIFICATION_README.html Basically, have a list of valid recipients, or dynamically build a cache with reject_unverified_recipient. Wietse
