sqwebmail and localhost problems

Hello, 

In my company we use sqwebmail which has been designed by another company.
but ewe have problems. when deleting the mails in the inbox area, screen can 
not refresh it so deleted mails still be on the screen.that's why, I go to 
the files area then again turns to the inbox.Now deleted mail is not there.
I want to modify webmail, add new properties, changing the company logo or 
how can solve my problems? 

could you give me an idea please. 

Thank you
ilker