Take the 2-minute tour ×  I'm not 100% sure that this is a
problem caused by BES, but it showed up soon after my email
account was tied to a Blackberry, so this is my first guess.  I
get my email from an Exchange server, but I connect to it from
Thunderbird using IMAP. Everything mostly seems to work fine
with this.  About the time that I got my Blackberry and had my
email account enabled on the BES, I started to see a strange
occurrence in Thunderbird. When I receive an email, it shows up
in Thunderbird. Then it disappears. Then it shows up again. It
usually disappears two or three times before it settles down.  I
have tested this independently of Thunderbird by opening an IMAP
session and IDLE-ing in my INBOX. It shows that Thunderbird is
just doing what the Exchange IMAP server is telling it to do.
Here is a log of the receipt of a single message:  + IDLE
accepted, awaiting DONE command. * 150 EXISTS * 151 EXISTS * 151
EXISTS  What that's saying is that it received a new message
number 150 and out of those