We use Zimbra Community Edition at my company. I like Mail, but I switched from Mail to Thunderbird a while back because, quite frankly, Mail's IMAP support st

We use Zimbra Community Edition at my company. I like Mail, but I switched from Mail to Thunderbird a while back because, quite frankly, Mail's IMAP support stinks. It is just not very robust. Moderately sized mailboxes lose sync with the server, causing duplicate messages and related issues. Second problem: iCal sucks for corporate scheduling. Setting up attendees, and viewing free-busy time is ridiculously complicated. Anyone who has used Outlook/Entourage laughs at iCal. Lightning/Sunbird, however, is wonderful. Fully supports CalDAV and the Free/Busy extensions. I manage about two dozen Macs here and have had this issue repeatedly against a Zimbra backend. I have a few users on Thunderbird 3.0 betas, and those problems just disappeared. Once Lightning 1.0 comes out, I will be forcing everyone to switch to Thunderbird/Lightning on both Mac and Windows. The Zindus extension for Thunderbird syncs Gmail Contacts and the Zimbra Global Address List to Thunderbird. Lacking this, LDAP search works great against Zimbra. The resulting solution: Zimbra / Thunderbird / Lightning / Zindus is, as far as I'm concerned, an Outlook/Exchange killer for small to medium sized companies.