As with the Exchange edition, this plug in blocks undesirable attachments by filtering names or file extensions.

The primary goal of Avast SMTP Server Edition is to effectively filter all SMTP traffic. It has been proven that SMTP is the number one source of infection. It is vital therefore for an antivirus solution to be deployed on SMTP servers (or gateways). By keeping the code as small as possible, our solution boasts outstanding performance and robustness and uses very little memory space.

Integration with the IIS

Thanks to tight integration with Windows SMTP Service (part of Windows Internet Information Services - IIS), avast! is able to detect and remove viruses from both inbound and outbound messages before they reach their recipients. This is done by connecting to the SMTP Service and simultaneously screening all messages before they're allowed to proceed to the delivery queue. We can therefore guarantee that no message will slip through untested.

Intelligent Actions

avast! SMTP Server Edition offers a wide variety of automatic actions that can take place whenever a virus is found. Separate rules can be specified for inbound and outbound traffic, and also for untestable (e.g. encrypted) messages. avast! is also able to change the message's body/headers and add information about the message's infection status (this feature can be activated for both infected and clean messages).

Attachment Blocking

Avast, SMTP Server Edition also contains a simple attachment blocker. You can specify filters for file names and extensions (such as *.pif or Love*.vbs) of attachments that will be removed from all inbound and outbound messages. This is a very simple yet extremely powerful weapon for effectively fighting both known and unknown malware.

Alerting & logging

As with any server-side software, it is very important to provide effective means of monitoring.  For this reason Avast offers a wide range of possibilities. These include thorough notification via e-mail and avast's built-in Notification Manager (which supports a number of other transport protocols), rich logging features, and performance counters.

The e-mail notifications are "intelligent" due to their predefined limits (to avoid flooding the server with avast's own messages) and also because they are only sent to respective message senders if these are really the originators of the infected mail (i.e. if the From: fields of the message have not been forged).

Automatic updates

The SMTP Server Edition uses the same modules as Avast Server Edition itself, resulting in unparalleled speed and size of updates. The updates can either be installed automatically by the system, or manually. It is also possible to set the system up so that it asks the administrator before installing any updates.

The Exchange module also recognizes Avast PUSH iAVS messages. Therefore, avast's unique PUSH iAVS feature is fully compatible with the SMTP Server Edition, with no additional modifications to settings required.