I mentioned this in another thread... but Mozilla/Thunderbird (not MZLA) should really concentrate more on feature-rich support. Specifically better calendar and provider integration.<p>Second to this, they should probably work on their own first class mail and calendar server as at least open core, and probably as SaaS as well. As much as I like some of the mail hosts out there, for some, the ability to self-host is big. The various pieces and software you have to cobble together are cumbersome, and even then, you don't get anything close to what Exchange+Outlook gives you.<p>It would be nice to see Thunderbird fill this space, it used to be what I would consider a best of breed email & newsgroup client, now, I'm not sure I would say anything close to that.