Long story in short.
Follow below steps.
1. Install "ssmtp" package in Centos.
yum install ssmtp
2. Now open /etc/ssmtp/ssmtp.conf file and change below mentioned details.
mailhub=smtp.gmail.com:587
Hostname=host@example.com #not sure if this really matters
FromLineOverride=YES
UseSTARTTLS=YES
AuthUser=test@gmail.com
AuthPass=Th!sP@ssword!
TLS_CA_File=/etc/pki/tls/certs/ca-bundle.crt
3. Now open "/etc/ssmtp/revaliases" file and add below line.
root:test@gmail.com:smtp.gmail.com:587
4. Now run alternatives command and select sendmail.ssmtp as a default mta
alternatives --config mta
5. Now you can test mail using mutt.
