Sending email via Gmail relay through postfix

<yambe:breadcrumb>Postfix_server_configuration|Postfix server configuration</yambe:breadcrumb>

Sending email via Gmail relay through postfix

To send email via Gmail relay through postfix use:

1. Configure gmail to use less secure apps using:
   1. Login into Gmail account and go to Settings -> Accounts -> Google Account Settings
   2. In "Google Account Settings" go to Sign-in and Security.
   3. In Sign-in and security change "Allow less secure apps:" to ON
2. yum -y install cyrus-sasl cyrus-sasl-plain cyrus-sasl-lib postfix mailx
3. Note that without cyrus-sasl and related packages error no worthy mechanisms found would be received while authenticating to Gmail via postfix. Refer https://serverfault.com/questions/325955/no-worthy-mechs-found-when-trying-to-relay-email-to-gmail-using-postfix
4. Set at least following in /etc/postfix/main.cf for mail system to work properly:

   myhostname
   mydomain
   myorigin
   inet_interfaces = all
   inet_protocols = ipv4

5. edit /etc/postfix/sasl_passwd and put something like

   smtp.gmail.com	<gmail-email-address>:<gmail-password>

6. Create hash postmap of sasl_password using:

   cd /etc/postfix
   chmod 600 sasl_passwd
   postmap hash:/etc/postfix/sasl_passwd

7. edit /etc/postfix/main.cf and after relayhost comment lines insert

   smtp_sasl_auth_enable = yes
   smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
   smtp_sasl_security_options =
   smtp_tls_security_level = may
   relayhost = smtp.gmail.com:587

8. service postfix restart
9. echo "Test email using postfix" | mail -s "Gmail relay test" saurabh@sbarjatiya.com
10. Look for successful email being sent or errors logs using:

    mailq
    tail -50 /var/log/maillog

    Logging into above configured "Less secure Gmail" account via browser also helps

To troubleshoot look at /var/log/maillog. In log lines look at value of ctladdr such as 'ctladdr=saurabh (501/501)'. Then look at /var/mail/saurabh or login as user saurabh and use 'mail' command to see error message sent by Gmail server.

<yambe:breadcrumb>Postfix_server_configuration|Postfix server configuration</yambe:breadcrumb>