MUA: Webmail Which is better?

[borgesbruno]

Hello, I need a solution for my webmail server, but I am in doubt which to use what you suggest me?
I know these:

RoundCube, Atmail, SquirrelMail, Horde and Emexis-Webmail.

Thanks

[zombykillah]

I am using eGroupware ...
Part of it is a web-mail.

But I've problems syncing contacts with Windows Computers ...
Outlook should work, but isn't.
Thunderbird ... did work ... but it always updates on it's own to an not working version.

Syncing the calender works with Lightning without any problems.
IPhone should work, but doesn't ... without any reported errors.

However, the Mail-Part works fine with IMAP.

P.s.: I love should work ...