Sometimes when trying to send emails , the following error shows up :
“550 postmaster verification failed”
This is one way of verifying that the sending server is in fact the real sender and not relaying and also the email is being sent by a genuine source.
Create a mailbox named po[email protected] on the domain which is sending emails.
This should fix it.
Some mail server admins are now implementing this. If someone has any other suggestion on this then do post it here.