If you search this discrepancy, there are a lot of results affecting a multitude of platforms. This isn't new. One thought was a storage limit for the Trash folder. I thought there was only a limit for the entire profile but apparently an admin could have inadvertently set a limit on a particular server or account(s).
This seems odd in the realm of administration, but I recently had some weird sub-folders suddenly appear in my Trash folder. I didn't create these sub-folders and then delete. Somebody or something created and then deleted these folders. It had to be an administrator tinkering on the server. The link is an image of these weird folders.
You can sort the content of your Trash folder by size.
Another thought was the IMAP setting in your Outlook. Try deleting this IMAP connection, deleting the email in Webmail and if it's gone, rebuild your IMAP connection in Outlook.
These are just stabs in the dark but there is something corrupt affecting this one email from Best Western. It seems as though it's caught in this weird volley of rules. You have no rules other than IMAP. Maybe you could also try to forward the email to yourself and then delete the forwarded email. This may break the headers within the haunting original email.
forums.cox.com/.../Webmail.bmp
