I see the bug of contradiction, here.
But then, maybe - that's just my fault (for reading your issue more than a dozen time.)
I think that it is my bad English but there is no contradiction.
I wrote first:
The mail is gone! So I check the recycle Bin of the new MW and there it is. So I restore the email and I went back.
-> then next you can read that I have closed the new MW and then I wrote:
Yes that is the big problem here! There are mails, say it again, totally gone so also no viewing at the MWP Recycle Bin (I talk of no other Bin then the bin of MW!) and also no chance to restore them. I would advise you to read good my problems and then you will realize that it is really a nasty bug! It can be nothing else.
So the mail of spamcop was seen in the bin of MW after MW deleted it for the first time. Also notice that I had Spamcop in my friends list and with the basic settings of MW it cannot be deleted. Second I had closed the program and started up again and then there are no spamcop mail in the bin of MW or anywhere else. Where is that email? And this happen to me with more than one email but the spamcop mail I had noticed right away.
The issue you are facing is peculiar to just your own system - otherwise, this forum would have been full of complaints (if this was truly a bug.)
I had noticed when I had +-20 mails in MW and I must read the most of them but had no time and a couple of days I had the time for some mails and there were mails gone. So I do not noticed it at the moment but a day or two later and I had never deleted the mails that was missing because one of them had a invoice of a product that I have bought and that was the warranty also for that product. So I know what I'm talking about and maybe I'm not the only one but the first that had noticed it because if there are no records of some deleted mails, you must exactly now what emails you have. If not you will not noticed it.
But I'm on the old MW now and now issues whatsoever. Not with reading mails and that they are back after a day or so as unread, no situations where I get a mail from B and from A and after a day or two I see the mail B with the title of A but I can nowhere see the text of mail A and the third is that I have noticed when I have emails on my account. Say 15 but in MW I see only 13-14 mails. So it does not get all the emails all the time from my account.
And I'm sure that I'm not the only one here with these issues! I'm sure of it because I know something about programs because testing is my hobby for years and I have a degree in IT. So when I say the new MW is buggy, then it is buggy or otherwise there was not much negative to tell in the first place!