question

[Reza Shahrabi]

hi
I have a problem with FreeBSD Mail Server.
from few days ago in mail server this Message is prompted :
" Aug 26 8:35:55 molavi ( the name of this server ) qmail : 1061873351 . 361023 alert : unable to append a bounce a message : HELP ! Sleeping ..... "
and form this days we are not receiving any mail . so i would like to say me what should i do .
and what does it mean ? 
thanks
Reza shahrabi