Hi there, Thanks for the reply. Yes I do:
smtpd_recipient_restrictions = permit_sasl_authenticated, permit_mynetworks, reject_unknown_reverse_client_hostname, reject_unknown_client_hostname, reject_unknown_sender_domain, reject_non_fqdn_recipient, reject_unauth_destination, #reject_unauth_pipelining, reject_unverified_recipient, reject_unknown_recipient_domain, #reject_invalid_hostname, reject_rbl_client bl.spamcop.net, reject_rbl_client sbl-xbl.spamhaus.org, check_recipient_access mysql:/etc/postfix/mysql_hold.cf Huge thanks Em ter., 29 de dez. de 2020 às 10:28, <ludic...@gmail.com> escreveu: > Hi Rafael, > > > > quick thoughts. Do you have > > > > smtpd_recipient_restrictions = reject_unauth_destination > > > > in your main.cf? > > > > The request should be rejected and not be queued. > > > > Greets, > > Ludi > > > > *Von:* owner-postfix-us...@postfix.org <owner-postfix-us...@postfix.org> *Im > Auftrag von *Rafael Azevedo > *Gesendet:* Dienstag, 29. Dezember 2020 13:38 > *An:* Postfix users <postfix-users@postfix.org> > *Betreff:* SPAM attack from bounce techniques > > > > Hi there, > > > > I've noticed that one of our servers is receiving a huge amount of > unauthorized requests. > > > > User connects to our server and tries to send an email to any destination. > Our servers denies the message because user is not authenticated. Then, a > bounce is generated to the source address, which was fake and turns to be > the final destination, so at the end, the email is actually sent as a > bounce, proliferating lots of spam. > > > > Is there a way to avoid this? > > > > Thanks in advance. > > > > BR, > > > > Rafael >
