Configure postfix as relay for OS X

macosx-configure-postfix-as-relay.md

Configure postfix as relay for macOS Sierra – Mojave

• Source: http://www.developerfiles.com/how-to-send-emails-from-localhost-mac-os-x-el-capitan/
• Source: http://budiirawan.com/install-mail-server-mac-osx/
• Source: https://apple.stackexchange.com/questions/32228/whats-the-correctly-way-to-make-postfix-run-permanently-on-lion-not-server

1. Edit postfix configuration file

1. sudo vi /etc/postfix/main.cf
2. Ensure that the following values are set:

   mail_owner = _postfix
   setgid_group = _postdrop
   

3. Add the following lines at the end of the file:

   # Postfix as relay
   #
   #Gmail SMTP
   relayhost=smtp.gmail.com:587
   #Hotmail SMTP
   #relayhost=smtp.live.com:587
   #Yahoo SMTP
   #relayhost=smtp.mail.yahoo.com:465
   # Enable SASL authentication in the Postfix SMTP client.
   smtp_sasl_auth_enable=yes
   smtp_sasl_password_maps=hash:/etc/postfix/sasl_passwd
   smtp_sasl_security_options=noanonymous
   smtp_sasl_mechanism_filter=plain
   # Enable Transport Layer Security (TLS), i.e. SSL.
   smtp_use_tls=yes
   smtp_tls_security_level=encrypt
   tls_random_source=dev:/dev/urandom
   

2. Create sasl_passwd file

1. sudo sh -c 'echo "\nsmtp.gmail.com:587 your_email@gmail.com:your_password" >> /etc/postfix/sasl_passwd' Replace your_email@gmail.com and your_password with actual values.
2. sudo postmap /etc/postfix/sasl_passwd

3. Autorun postfix on boot and restart postfix

1. Copy the postfix master plist out of System folder.

   sudo cp /System/Library/LaunchDaemons/com.apple.postfix.master.plist /Library/LaunchDaemons/org.postfix.custom.plist
   

2. sudo vi /Library/LaunchDaemons/org.postfix.custom.plist

3. Change the label value from com.apple.postfix.master to org.postfix.custom

   Remove these lines to prevent exiting after 60s

     <string>-e</string>
     <string>60</string>
   

   Add these lines before </dict>

     <key>KeepAlive</key>
     <true/>
     <key>RunAtLoad</key>
     <true/>
   

4. Relaunch the daemon.

   sudo launchctl unload /Library/LaunchDaemons/org.postfix.custom.plist
   sudo launchctl load /Library/LaunchDaemons/org.postfix.custom.plist
   

5. Check that daemon has started.

   sudo launchctl list | grep org.postfix
   

4. Turn on less secure apps for gmail

In Gmail we must switch on the option "Access for less secure apps", otherwise we will get the error: SASL authentication failed

5. Test

1. echo "Test sending email from Postfix" | mail -s "Test Postfix" youremail@domain.com

   Change youremail@domain.com with valid email with mailbox access for easy checking.

2. Check mail queue and possible delivery errors with mailq.

3. Check mail log with tail -f /var/log/mail.log.