On Wed, Jun 17, 2015 at 10:00:29AM +0300, Michael Peter wrote: > The reason i am asking for that in order to block some spam attacks on our > email mail server that using empty email senders
For some sites it is safe to use: http://www.postfix.org/postconf.5.html#reject_multi_recipient_bounce provided no bounces of mail *from* lists are expanded upstream of the MTA in question, and arrive as a legitimate bounce to a list of users. Otherwise, one SHOULD NOT block email from empty sender addresses, unless it is determined to be undesirable for other reasons. -- Viktor.