You need to set up either SPF or DKIM, so GMAIL can detect spoofed mail. I would recommend SPF, its easiest.
Just add the following to your DNS: @ IN TXT v=spf1 ip4:<YOUR EXTERNAL MAILSERVER IP> -all (repeat the ip4 command if you have multiple servers, ip6 is for IPv6) Or: @ IN TXT v=spf1 mx -all If your incoming server(s) is same as your outgoing. Från: owner-postfix-us...@postfix.org [mailto:owner-postfix-us...@postfix.org] För Motty Cruz Skickat: den 30 september 2016 00:49 Till: postfix-users@postfix.org Ämne: said: 421-4.7.0 This message does not have authentication information Hello, I see the following errors on SMTP server logs: E7AA017645 556 Thu Sep 29 15:43:13 us...@fqdn.com <mailto:us...@fqdn.com> (host alt1.gmail-smtp-in.l.google.com[74.125.69.27] said: 421-4.7.0 This message does not have authentication information or fails to pass 421-4.7.0 authentication checks. To best protect our users from spam, the 421-4.7.0 message has been blocked. Please visit 421-4.7.0 https://support.google.com/mail/answer/81126#authentication for more 421 4.7.0 information. o78si810588ita.33 - gsmtp (in reply to end of DATA command)) We are not spammers, were legitimate, full qualify domain name. Any ideas? Thanks, Motty
smime.p7s
Description: S/MIME Cryptographic Signature