Ah, but it has. It changes with each update. Besides, it is harmless to rule it out as the cause of any issue in Pegasus Mail. Below is a link to a Norton support webpage that explains how to exclude files and folders from Norton's Real Time Protection. In your case I suggest excluding C:\PMAIL. The article I linked to does not specifically state whether the exclusion includes all subdirectories but I suspect that it does, so excluding C:\PMAIL will also exclude your mailbox directory from Real Time Protection or what you commonly see referred to on this forum as "active scanning".

https://support.norton.com/sp/en/us/home/current/solutions/v20240116192643877

If you are concerned about nefarious files arriving via email, let me reassure you with this explanation of how things work. Malware in an email would arrive as an attachment. Hopefully you don't open attachments that you aren't expecting, but even if you did, when an attachment is opened from within Pegasus Mail it gets written to a temporary location where it will immediately be scanned by active scanning.

Brian

In my email received duplicate folder I keep getting this message on many attachments....

This message contains binary or non-textual data that cannot be previewed within Pegasus Mail.

Filename: Unknown

You can work with this file in the message reader's 'Attachments' page.

When you look in the Attachment tab of one of these messages, what do you see as an attached file(s)?

This is an example of the Attachment tab of a message that contains a plain text version, an HTML version, and two attached .PNG images.
NOTE: You will likely not see "See-filename" in the Type column. That is something I have implemented when attachments are defined by the sender as the generic Content-type of "Application/Octet-stream".

FWIW, the message you quoted is the result of Pegasus Mail not being able to display the content of an attachment as a Preview possibly because it doesn't contain an internal content viewer capable of displaying it, or possibly because the attachment is malformed.