Problems in sendmail

[abbasi]

hi
I have a problem in sendmail regarding to delete the mails of a single user and moreover if i want to delete the junk mails of a specefic user what should i have to do.it means i dont want to delete all the mails of a specefic user .

2-->if i go to the web interface of a sendmail server for some user it opens the account but shows no mails in the web inbox.and if i click on the inbox icon then it becomes hanged.

3-->what is the method to to take the backup of all the mails in sendmail server .