I just wanted to know which is the best webmail software/script but serverload-wise, we've been using a customized version of Uebimiau for a while, even when it's not as flashy as some webmails I've seen it works excellent.
However lately we've faced some problems with customers using mailboxes over 600 Mb, it seems to take a while to load and the server load goes up immediately. Now we've been handling it over 1 year, but now we are going to get a few more customers with huge mailbox requirements so we're thinking about migrating to another webmail system.
It would be better if it's open source as that would allow us to do some required customizations, but we're open to try almost anything.
Thanks in advance for your advices.
Edit: forgot to add that it will be used on *nix servers.