[Users] New member - Microsoft Exchange query

[Liz]

I've been a user of this software for some years and this is the first
time I've struck a problem that required finding the mailing list. I
didn't find any answer on my websearch, so if this is a well known
problem that I've missed, I apologise.

I have one IMAP account which connects with a Microsoft Exchange
Server. (I have no choice in this).
This worked faultlessly for about 6 months, and recently I found I had
missing mail. The emails which were missing were being routed into a
Trash folder, I wasn't subscribed to the Trash folder, so I was quite
unaware of what was happening.

I have had a long email conversation with the administrators of this
mail server. Basically I believe there is a filtering error on their
side, and they believe there is a filtering error on my side.
I have not set up a filter to put any mail from that server into Trash
on that server. I was filtering important mails and putting them onto
my desktop, but some of those mails have gone straight to Trash, and
not been filtered into the correct folder on the desktop.

I don't use any other software with the mail server, no phone, don't
use the web interface etc.

Because Claws-Mail is unknown (perhaps frightening) I am fighting an
uphill battle to get the administrators to consider that they may have
a filtering problem. I'm now up to my fifth Help Desk person in this
quest.

I think that it is unreasonable to claim that any mail client accesses
an IMAP account, and randomly moves mail into another part of the
account (two identical mails may go different places) when it isn't
even subscribed to that part of the account. 

I've searched my filtering.log for strings which would show that
Claws-Mail is filtering the mail into that account, but I drew a
negative.

?
Questions
Has anyone else heard of this happening?
Is anyone aware of a logical sequence of events which might cause
Claws-Mail to filter mail this way?

Liz