I don't mind that but can't understand why, having created two folders on Samsung when I was using POP3, they suddenly disappeared on my mobile but appeared on BT Mail under My Folders. I don't need them on BT Mail - only on my Samsung.
I have no idea how that happened. Any folders you create on the Samsung as POP3 won't appear in webmail.
Just humour me, and try downloading and using Blue Mail configured as IMAP and see if that behaves as it should. Force stop the Samsung app but no need to delete it.
I've installed Blue Mail and Force Stopped Samsung Email. However, Blue Mail will not run as there are "too many simultaneous connections".
Hmm, that's odd. Have you got any other devices accessing your mail.
I don't have any problems with Blue Mail, Outlook and webmail all running at the same time on the same account.
Just see if Blue Mail behaves how you expect it to. I.e delete a mail, see it go to Trash, delete it from Trash and ensure it doesn't reappear when you resync.
Suggest you stick with Blue Mail if all is working.
I suspect the Samsung app may be confused as to whether it is POP3 or IMAP and not behaving as either.
You could always try deleting and reinstalling the Samsung app.
If you stick with Blue Mail, either delete the account on the Samsung app or delete the app.