View source for Postfix for Gmail

This is how to setup Postfix to use Gmail as a relay host, so it can send email via Gmail, e.g. for output of cronjobs etc.

== Secrets Configuration ==

This page follows the configuration defined in <code>[https://github.com/Mic92/sops-nix sops-nix]</code>, but you can use any [[Comparison of secret managing schemes|secret managing scheme]].

== Add a "postfix/sasl_passwd" secret ==

Create an app password specifically for this postfix installation at https://myaccount.google.com/apppasswords (logged in as you).

You end up with a 16 character string separated by spaces. Put that in a sops secret:

  nix-shell -p sops --run "sops /etc/nixos/sops-secrets.yaml"

Create this entry, using the 16 character string without spaces (''Don't use the "abcdefghjklmnopq" string below. It won't work :-)'' ):
  
  postfix:
      sasl_passwd: '[smtp.gmail.com]:587 you@gmail.com:abcdefghjklmnopq'

== Configure Postfix ==

  sops.secrets."postfix/sasl_passwd".owner = config.services.postfix.user;

  services.postfix = {
    enable = true;
    relayHost = "smtp.gmail.com";
    relayPort = 587;
    config = {
      smtp_use_tls = "yes";
      smtp_sasl_auth_enable = "yes";
      smtp_sasl_security_options = "";
      smtp_sasl_password_maps = "texthash:${config.sops.secrets."postfix/sasl_passwd".path}";
      # optional: Forward mails to root (e.g. from cron jobs, smartd)
      # to me privately and to my work email:
      virtual_alias_maps = "inline:{ {root=you@gmail.com, you@work.com} }";
    };
  };

== Profit ==

  sudo nixos-rebuild switch

Send an email explicitly to you@gmail.com

  nix-shell -p mailutils --run \
    'echo "This is a test email." | mail -s "Test Email from NixOS" you@gmail.com'

Send an email explicitly to root that gets sent to you@gmail.com and you@work.com (if you opted in for virtual_alias_maps)

  nix-shell -p mailutils --run \
    'echo "This is a test email." | mail -s "Test Email from NixOS to root" root'

== References ==

[https://discourse.nixos.org/t/porting-my-postfix-gmail-smtp-to-nixos/30286 Porting my postfix gmail smtp to nixos] on the NixOS Discourse.


[[Category:Mail Server]]
[[Category:Server]]