|Connection filtering with real-time block list|
|Recipient Confirmation from final MTA|
|Sender ID lookup|
|Bayesian / Heuristic Filtering|
|Customized spam filtering|
|Rule base scoring|
|Updated and integrated content Message Filter|
Dealing with the concerns over spam, viruses, e-mail attacks, and other email related security threats, best practices are followed to ensure that it has the highest level of defense possible while still maintaining usability:
Using a multifaceted defense system for the most efficient results.
Scan at the perimeter level.
Delete infected messages.
Domain and email based blacklisting / whitelisting.
Developing a defense against viruses and spam is not enough, security against other e-mailrelated threats, such as:
Directory harvest attacks.
Global Accept and Global Deny Lists.