Limit Uploaded Files To Certain File Extensions

This folder setting controls which file extensions are allowed when files are uploaded into the folder.

It helps enforce file type policies, for example allowing only document formats like .pdf or .txt and blocking all other file types. This supports compatibility with downstream systems and helps meet compliance requirements.

This restriction applies to any action that places files or folders directly into the folder, including uploads, Inboxes, Share Links, renames that result in restricted extensions, manual copy or move actions, and automated processes like Syncs and Automations.

By default, the setting behaves as a whitelist, meaning only the extensions you specify are accepted. You can switch the setting to blacklist mode to block specific extensions instead.

If this setting is not applied to the folder directly and is not inherited from a parent folder, the folder accepts files of any extension.

This rule applies to all subfolders unless explicitly overridden at a deeper level.

Moving or copying files or folders into restricted folders fails when the destination path has stricter file extension rules than the source path.

Overriding Settings in Subfolders or Excluding Subfolders Entirely

Administrators with adequate privileges can set the Limit uploaded files to certain file extensions option on a subfolder to define its own extension rules, overriding what the subfolder would otherwise inherit from its parent.