Architecture

Connection filtering with real-time block list
Recipient confirmation from final MTA
Recipient lookup
Sender ID lookup
Bayesian / Heuristic Filtering
Attachment filtering
Customized spam filtering
Rule base scoring
Antivirus scanning
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.

  Attachment filtering.

  Domain and email based blacklisting / whitelisting.

Developing a defense against viruses and spam is not enough, security against other e-mailrelated threats, such as:

  Mailbombing.

  Directory harvest attacks.

  Connection Filtering.

  Global Accept and Global Deny Lists.

  Sender Filtering.