Install both then your users will not have to be stuck to one. They both are good.
They are getting one. I don't want to deal with the incompatibilities and issues stemming from differences in proprietary features.
I put together an analysis of what DirectAdmin offers. Let me know where you disagree:
- Uebimiau has arguably the nicest and most functional interface. However, it hasn't seen a developer since 2001, and thus a risky choice. You would also need to patch the code for 64 bit machines.
http://help.directadmin.com/item.php?id=133 It has the same vulnerability that RoundCube just fixed except it will never be fixed.
- SquirrelMail is very actively maintained, but hard to look at in standard form. It's one of the defaults for DirectAdmin installs. It appears to be the most secure and gives the least trouble. There is a skinned SquirrelMail templates available called NutsMail! that is nicer than any of the other options listed here, but it's $67/server. It also includes calendars etc. and is very configurable.
- RoundCube is an Ajax-based client. It is actively maintained but development has been steady but very slow. It uses MySQL for its address book in exchange for not needed its proprietary directories scattered about the disk. It's one of the defaults for DirectAdmin. Requires PHP 5. It recently had a serious vulnerability but was fixed.
- @Mail Is another AJAX based client. It is very actively maintained. Better known is its commercial based server product which is very capable. However, they also now have an open source version that can be installed by DirectAdmin. Their sales pitch is, "Users also can jump from the free client to the commercial version, which adds calendaring, and a groupware and antivirus module." Thus, they will walk a fine line between what they will allow for free. It's expensive for a few users and very inexpensive for a lot of users. I've not used it personally. There is a DirectAdmin discussion here:
http://www.directadmin.com/forum/search.php?searchid=1662507,
http://www.directadmin.com/forum/showthread.php?t=26994&highlight=AtMail, and other posts. Apparently it violates standards and thus doesn't play well with othe IMAP clients. Hopefully there is gain to pay for the pain. It's also available from the FreeBSD ports tree.
Thanks