(1) Enterprise
(2) GMail
(3) Google Sites email address (GMail for business)
For #3, the BB seems to be "threading" conversations, even though it is not for #2.
Personally, I'm not into the threading and want to get rid of it. Is there any way? I think its weird it is threading the google sites email account and not the regular GMail account...
Are you using the enhanced gmail plugin on your device? If so, by nature it will thread your messages. You can view them in the default messages folder to unthread them, or if you know how to remove .cod files from your device with a program like BBSAk, you can do it that way as well.