Squirrelmail use very CPU usage, I did have performance problem with this package I don't recommend webmail based php and perl. They don't work with very users, they have very problems with thousand account. You should use sqwebmail or another webmail based in C language.
Somebody know others webmail based in C++?
while i agree that php/perl based products use more CPU, it's not helpful to say that they _don't_ work with very [many] users, as it's simply untrue. I'm running squirrelmail and it runs just fine - on a Sun Ultra 2 200mhz. not exactly a speed demon. i *am* using a software PHP accelerator, and there's no good reason for anyone to run squirrelmail without one - it dramatically reduces CPU demand.
squirrelmail is debateably the best webmail client around. My customers prefer it by a large margin over the other three webmail interfaces i offer (as mentioned before, TWIG, IMP, and sqwebmail). sqwebmail is frankly quite lame in my opinion. it's extremely thin on features, as apparently the author considers features to be bugs. the performance benefit of a webmail client that acts directly on the maildir is offset by the dreary, featureless interface.
Paul Theodoropoulos http://www.anastrophe.com