Attachment & MIME Filter
Configure attachment and MIME filters: block file types, analyze archives.
Attachment & MIME Filter – Control of Attachments and File Types
The Attachment & MIME Filter from Conbool protects your mailboxes from malicious or unwanted files.
You can precisely define which file types are allowed, inspected, or blocked.

Enable Attachment Checking
- Function: Enables or disables the general inspection of attachments.
- Setting:
- Toggle to the right (blue) → active
- Toggle to the left (gray) → disabled
Enable ZIP/RAR Analysis
- Function: Unpacks compressed archives (e.g.,
.zip,.rar) and inspects their contents as well.- Increases security by detecting hidden malicious files
- May slightly affect processing speed
- Setting:
- Toggle to the right (blue) → active
- Toggle to the left (gray) → disabled
Maximum Attachment Size (MB)
- Function: Defines the maximum allowed size for email attachments.
- Setting: Numeric field (size in MB)
- Example:
50→ Attachments up to 50 MB allowed
Blocked File Types (Predefined)
- Function: Selection of common file extensions that are blocked by default (e.g.,
.exe,.js). - Setting:
- Display of the number of selected types (e.g., "3 selected")
- Selected extensions appear as tags (
.exe,.js, ...) - Selection via dropdown or checkboxes
Custom File Types
- Function: Individual extension of the block list with additional file extensions.
- Setting:
- Text field: Enter the extension (starting with a dot, e.g.,
.sh,.bat) - Button: Adds the extension to the block list
- List: Shows already added extensions with a delete option (trash icon)
- Text field: Enter the extension (starting with a dot, e.g.,
See Also
- Policies – Apply attachment filters specifically to certain users or groups through policies.
- Feature Overview – Overview of all MailGuard modules.