Imap stores the emails on the server not on the local computer UNLESS you
save a copy locally.
Check the current message stores (Tools | Options |Maintenance tab | Store
Folder button for that location).
Can't recall exactly at the moment but I believe IMAP DBX files were stored
with a different name and the dbx file extension.

I dont'have this imap account to save already the mail of this old
account.
In the folder of dbx file there aren't the mails that i search.... this
has been my first action.
The extension of db mail for imap account is .dbx, the same of pop3?

Someone know a program file recovery to resolve this problem?
Thank Ant