squirrelmail Vs. horde/imp, VS sqwebmail

Hello
We plane to setup a huge mail server that should handle 20k users. Most will use webmail. And some email lists
I hear that Qmail based mail system should be best for us. (Is that true?) .
Anyway I would like to know which webmail software will be best for us. We will need to customize it. Add language support (some of the student's language is not included with squirrelmail, horde/imp, and sqwebmail.
Also very important will be the performance. For such huge mail box - which will give us best performance?
what are the pros and cons for each of the bove webmail apps?
Thanks for ANY input

 

 

 

 

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