Thx for the respons
I have setup sasl auth by dovecot -----Original Message----- From: owner-postfix-us...@postfix.org <owner-postfix-us...@postfix.org> On Behalf Of Viktor Dukhovni Sent: 03 June 2019 16:58 To: Postfix users <postfix-users@postfix.org> Subject: Re: smtp relay server security > On Jun 3, 2019, at 9:02 AM, De Petter Mattheas > <mattheas.depet...@jandenul.com> wrote: > > For the moment we have a rule that only allow mail from exchange server > address to postfix (relay server), but when somebody spoofs this address mail > gets accept and you can send your mail to anybody as anybody. > > When I check: > [administrator@eqx-mailman02 ~]$ sudo postconf -a [sudo] wachtwoord > voor administrator: > cyrus > dovecot You can configure SASL authentication on both ends (client on Exchange, server on Postfix) and require SASL authentication for relaying: http://www.postfix.org/SASL_README.html or you can require a TLS client certificate: http://www.postfix.org/postconf.5.html#check_ccert_access http://www.postfix.org/postconf.5.html#relay_clientcerts -- Viktor. ************************************************************ Any reaction to this e-mail or any other mail, including any files transmitted therewith to sender's e-mail address(es) shall be dealt with not as private, but as business communication(s) and shall be registered as such. ************************************************************