MailCleaner Support

Exchange does not natively reject invalid addresses during the SMTP connection.
This can cause problems for MailCleaner customers who select the SMTP Callout option.
However, Exchange can be configured to reject invalid addresses, resulting in a “550 5.5.1 User unknown” error. MailCleaner, in turn, can bounce these messages.
This will protect the infrastructure against Denial of Services and the user count will reflect only valid addresses in the system.

To configure this ability on the Exchange server, follow the documentations:

Exchange 2003 - 2007 -> https://www.mailcleaner.net/downloads/MailCleaner_Exchange07-03_config.pdf

Exchange 2013 - 2016 -> https://www.mailcleaner.net/downloads/MailCleaner_Exchange_13_16.pdf