From http://www.fossamail.org/: Are there other alternatives than Thunderbird for a compatible product?
Have you tried Evolution? The version in Ubuntu's repositories is outdated but you can install official PPA to keep it to latest.
at least it is always a bad idea to run derivates off from a main streamed product. i read something about a converter TB -> FM, thats same problem when returning from palemoon to firefox. same for other browser based mailers - opera 12 mailer=dead end, new opera mail= dead end, mailbird (chromium) = dead end, emclient = dead end, thunderbird=dead end, thebat = dead end. most mailers can import from main stream - outpost, thunderbird, maybe 2 more, but thats it. export will lose structure in most cases. it is hard to find a product where data is transparent, open for external access - but secure.
This may help (hopefully not hurt!) some folks! I installed Thunderbird, opened it and the exact copy of all Fossa was there. I uninstalled Fossa and Thunderbird still well and good. Perhaps it had to do with the way I originally installed Fossa, or what I did was what the poster meant by "copying profile". All I know is I kind of have issues hunting down Mozilla profiles so was relieved!
maybe fossamail works with same folder: %appdata%\Thunderbird. user had a paid mailer based on thunderbird, unfortunately those monks of developers used the same identifier as thunderbird for default mailer. running thunderbird made TB as default mailer, running the other made that as default. problem - he could not start TB when he had other opened last time.
Maybe this helps: http://www.claws-mail.org/faq/index...x_.2F_addressbook_from_.28some_mail_client.29.