/etc/ssmtp/ssmtp.conf

OUTLOOK:

root=name@outlook.com
mailhub=smtp-mail.outlook.com:587
UseSTARTTLS=YES
AuthUser=name
AuthPass=pass
rewriteDomain=outlook.com
FromLineOverride=YES
hostname=nom_de_la_machine

GMAIL:

root=name@gmail.com
mailhub=smtp.gmail.com:587
UseSTARTTLS=YES
AuthUser=name
AuthPass=pass
rewriteDomain=gmail.com
FromLineOverride=YES
hostname=nom_de_la_machine