Is there a way to completely reset the Mail app?
I had this issue on my Win 10 Desktop PC, and also with .132 update installed:
In the Mail app (setup with my IMAP email address) I can only view the Inbox. If I select another IMAP folder, such as Sent or Draft, it just sits there and freezes. I've removed the IMAP account (twice) and added it back, but still can only get it to view the Inbox folder. Other email programs, such as Thunderbird on the same PC, and Samsung Email on my Note can access all IMAP folders. Even the old Windows Live Mail on my Win 7 drive works fine.
Settings > Apps > Apps & features > Mail and Calendar > Advanced Options > Reset
-Eddie
Did the reset Mail (after removing the email account) then added the IMAP account back,
It still only works with my IMAP's Inbox folder, if I select any other folder (outbox, sent, spam, etc) the Mail app just sits there and freezes.
So I just tried my primary email in both IMAP and POP, and also two Comcast.net Email Accounts (IMAP) and no matter what, the Mail app keeps freezing up when selecting any of the mail folders.
I don't have this problem when using other mail apps on the PC (such as Thunderbird), and Samsung Email app or Outlook email app on my phone.
So it appears this issue is only with the Windows Mail app when trying to select other mail folders.