Configuring sendmail to relay mail through Gmail SMTP

1.                  Create User Account on Gmail.com.

2.                  Check network setting for lookup/telnet of smtp.gmail.com.

3.                  Create local user for sending mail through Gmail account to other mail account.

4.                  Edit /etc/mail/sendmail.mc file and add below parameters.

define(`SMART_HOST', `smtp.gmail.com')dnl

define(`RELAY_MAILER_ARGS', `TCP $h 587')dnl

define(`ESMTP_MAILER_ARGS', `TCP $h 587')dnl

define(`confAUTH_MECHANISMS', `EXTERNAL GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN PLAIN')dnl

FEATURE(`authinfo', `hash /etc/mail/auth/client-info')dnl

TRUST_AUTH_MECH(`EXTERNAL DIGEST-MD5 CRAM-MD5 LOGIN PLAIN')dnl

5.                  Create “auth” folder.

# mkdir /etc/mail/auth

6.                  Create “client-info” file and add below paramters.

# vi /etc/mail/auth/client-info

AuthInfo:smtp.gmail.com "U:gmail_test_user" "I:gmail_test_user@gmail.com" "P:gmail_test_user_password"

7.                  Change folder location and create database.

# cd  /etc/mail/auth/

# makemap hash client-info < client-info

8.                  Change permission of file and folder.

# chmod 700 /etc/mail/auth

# chmod 600 /etc/mail/auth/*

9.                  Compile configuration & restart service.

# m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf

# service sendmail restart

10.              Finally, send a test mail.

# echo 'this is a test mail'| mail -s welcome_to_testmail second_test_user@hotmail.com

11.              Check log message.

# tail -f /var/log/maillog

# tail –f /var/log/messages