My Norton anti virus program has not changed in years.
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.
[quote="pid:59127, uid:38672"]My Norton anti virus program has not changed in years.[/quote]
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.