In both cases, deleting obsoleted email messages from your inbox and email folders is the vital solution. But if you find that most of your email messages are useful for you, you may consider saving them to your local harddisk as a backup, and then delete the messages from the email server.
folder-collections = {imap.ust.hk}mail/[]
or
folder-collections = {uxmail.ust.hk}mail/[]
folder-collections = {imap.ust.hk}mail/[], Local_Folder c:\mail\[]
or
folder-collections = {uxmail.ust.hk}mail/[], Local_Folder c:\mail\[]

Folder-collection Local_Folderat the bottom of the screen.
