Download this tool: http://code.google.com/p/incredimail-converter-reynardware/downloads/detail?name=ReynardWareIncredimailConverter-0.53-Setup.exe&can=2&q=
Before running this tool, it may be prudent to remove the Deleted.imm file from the IncrediMail database, as the database holds messages that have been “permanently” removed, so the deleted database can have hundreds of junk messages that will take forever to export
Documents and settings\Local settings\applicaton data\IMIdentities\[identity key]\Message Store