We run many scripts on customer servers to email cdrs, backups etc, one problem with some mail servers is the mail gets rejected as it comes from email@example.com by default to fix this is simple and only takes a few lines.
Postfix MTA offers smtp_generic_maps parameter. You can specify lookup tables that replace local mail addresses by valid Internet addresses when mail leaves the machine via SMTP.
Open your main.cf file
# vi /etc/postfix/main.cf
Append following parameter
smtp_generic_maps = hash:/etc/postfix/generic
Save and close the file. Open /etc/postfix/generic file:
# vi /etc/postfix/generic
Make sure firstname.lastname@example.org change to email@example.com add :
Save and close the file. Create or update generic postfix table:
# postmap /etc/postfix/generic
# /etc/init.d/postfix restart
When mail is sent to a remote host via SMTP this replaces firstname.lastname@example.org by email@example.com mail address. You can use this trick to replace address with your ISP address if you are connected via local SMTP.
To set up gmail for delivery look at this