Not trying to revive the IMAP/POP wars, as everyone knows where I stand, but if your e-mail access is IMAP, there are a couple of things I'd suggest both as diagnostics and that should eventually resolve this:
1. Try a different e-mail client, Thunderbird springs to mind, temporarily to see if this same behavior exhibits itself there. The fact that your provider allowed an 8-day outage is just jaw dropping, and I suspect there are issues still on their end.
2. Try deleting your account under WLM, then re-creating it again. You lose nothing this way if you've used IMAP access and IMAP storage folders, all of which are server side, and all of which just re-sync when the account is created again. There could be something that somehow has become corrupted on the WLM side with your account, and starting fresh with WLM needing to create all the support structures on its side for that account might cure that.
Brian - Windows 10 Pro, 64-Bit, Version 1903, Build 18362
Many of the insights of the saint stem from his experience as a sinner.
~ Eric Hoffer