If you create a folder & the folder name ends with a period ' . ' then when you drag and drop items into the folder, the Quick Forward function is triggered. The user is prompted for 'Comments' and that input is prepended to the subject, and all the email participants ( TO/CC/BCC) are sent a copy of the email.
suggestions…
To fix, the function could also check for the field "$Flag" and if it exists or contains an F then it's a folder ?? ( see the view selection criteria for (Custom Expiration\Manage Folders) for an example of what to exclude. )