If you're noticing you have email drafts stuck in your Outbox, it may be the result of something going wrong that can only be seen with advanced diagnostics .
To find your Polymail debug diagnostics file, we'd recommend you follow these steps:
Open the Command Center ( Command ⌘ + J)
Type in Debug
Click Download Debug Diagnostics
Send that file over to us
It doesn't effect any other application or any files related to your macOS.