I moved from Mozilla Thunderbird to Zimbra Desktop client a few months back, and subsequently transferred locally stored mail into Zimbra without too much of an issue.

I would like to file my mail into thunderbird again and sync it with imap on gmail, as a redundancy backup, seeing as I use pop3 for ZD, my mail is only kept locally after retreival from serv, however the export feature on ZD spits out a zip with tar.gz files, which I am somewhat unfamiliar with in regards to being able to move them into a useable format for mozilla thunderbird.

Is there an alternative feature for localized mail storage in regards to file formats and export selections on ZD, if not how else can I transfer these locally stored ZD mail messages into thunderbird, is there a tool//utility to convert them in some way, or am I stuck with a proprietary format on all of my ZD stored mail messages?

Thanks in advance.