from the link that i posted earlier- https://www.howtoforge.com/tutorial/configure-postfix-to-use-gmail-as-a-mail-relay/
you are supposed to have these in your main.cf- relayhost = [smtp.gmail.com]:587 smtp_use_tls = yes smtp_sasl_auth_enable = yes smtp_sasl_security_options = smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt which i don't see in your paste.debian.net... from me configuring a couple of different virtual machines to use googles smtp you are going to have to change the line- smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd in debian to- smtp_sasl_password_maps = hash:/etc/postfix/sasl/sasl_passwd for some reason, that i don't know, in my two debian virts- cat /etc/os-release PRETTY_NAME="Debian GNU/Linux 8 (jessie)" dpkg -l | grep postfix ii postfix 2.11.3-1 cat /etc/os-release PRETTY_NAME="Debian GNU/Linux stretch/sid" dpkg -l | grep postfix ii postfix 3.1.3-1 the extra dir- /etc/postfix/sasl is created and then you have to run- postmap /etc/postfix/sasl/sasl_passwd to make things work properly. for your actual google settings you are going to have to go to- https://support.google.com/accounts/answer/6010255?hl=en and work your way through that. test your system by sending an email to another one of your email addresses from the machine that you are trying to send from (the one you're having problems with) mail -s test.hostmachine email.address once that is done then you can go back and flip the switch back to shut off the 'less secure' in your google account (worked for mine anyway) i have 6 virtuals of different distros that i have set up to relay through google.smtp for testing purposes by using that howtoforge link. check the change logs on what might have changed in postfix when you did your dist-upgrade (if postfix upgraded) and then trouble shoot it from there. google is your friend please remove my email address from your replies and only reply to this group instead of all thank you em
