14.5  Filtering Email Attachments

The attachment filter can be set in the Attachment Filter tab. If the message is captured by this filter, it will be delivered to the recipient without the attachment.

Attachment Filter tab

Figure 14.4. Attachment Filter tab


Enable attachment filter

Switches the attachment filter on or off.

Send a warning to sender ...

The sender will receive a warning from Kerio MailServer, that he/she has sent a message with a virus or blocked attachment.

Forward the original message to administrator address

The message will be forwarded (intact — with possibly infected or forbidden attachment) to the email address specified. It is not important whether the address is local or remote.

Forward the filtered message to administrator address

The message without an infected or prohibited attachment will be (apart from the actions selected below) forwarded to the specified email address as well. This can be used for verification of proper functionality of the antivirus and/or attachment filter.

List of filters

Displays individual filters. To the left of each filter there is a checkbox that you can use to enable or disable the filter. Use these checkboxes to switch filters off without the need to remove them.

After the Kerio MailServer installation, there is a list of several predefined filters. All filters are turned off and the administrator can choose to enable or remove them. This way for example executables (.com and .exe), Visual Basic scripts (.vbs), etc. can be filtered.

Use the Add button to add a new filter:

Description

Text description of defined filter.

Filter type (MIME type/File name)

Defines if attachments will be filtered based on file names or MIME type (Multi-purpose Internet Mail Extension).

Filename or file type specification

Enter either the file name (you can use the asterisk convention for e.g. filtering files with a certain extension — e.g. *.exe) or the MIME type name (for example application/x-msdownload or application/*). You can also choose one of the pre-set or MIME types.

Block the attachment...

An action will be performed as defined above the list of disabled attachments (described above).

Accept the attachment

Attachments will not be removed from messages and no other rules will be applied.