Hello everybody, now that i have a litle bit of time i want share and remember a great tip that i learned today, because one of my heavy mail users had a problem with webmail (squirrelmail 1.4.xx) show him next message :
Fatal error: Allowed memory size of 16777216 bytes exhausted (tried to allocate 4864 bytes) in /usr/share/squirrelmail/functions/mime.php(674) : regexp code on line 1
so, my logical answer was. mmm ok php needs more memory (memory_limit in php.ini), then i changed him but message still apear, so i take all my guns in google and got me at this place.
You need focus on next paragraph:
This error may also be caused by setting option $allow_server_sort to false in config.php
then i changed my config.php (squirrelmail) and works in flames! please do it if you can! now inbox’s loaded too fast! believe me! try it!

Thanks for sharing this information! I got the same problem with a mailinglist folder of several thousand postings. Easily resolved with the above change!