Change the IP address for outgoing emails in Plesk for Linux with Postfix mail server

1. Log in to Plesk.
2. Go to Tools & Settings > Mail Server Settings.
3. Set outgoing mail mode to one of the following options:
   • Send from domain IP addresses
   • Send from domain IP addresses and use domain names in SMTP greeting
   • Send from the specified IP addresses
4. Apply the changes.

   Note: The changes will be made in the Postfix transport map file /var/spool/postfix/plesk/sdd_transport_maps.db.

Here is Method to change IP