qmail queue

Hi list,

I notice that i have a huge queue.

/service/qmail-send: up (pid 1520) 2907232 seconds
/service/qmail-send/log: up (pid 1524) 2907232 seconds
/service/qmail-smtpd: up (pid 1519) 2907232 seconds
/service/qmail-smtpd/log: up (pid 1526) 2907231 seconds
messages in queue: 560
messages in queue but not yet preprocessed: 0

Going through the queue, i notice that almost all of the mails in the the
queue are junk mails sent out to invalid mailboxes.

I had checked the /var/log/qmail/current

 <at> 400000003ff925b10cd28244 delivery 194018: deferral:
Sorry,_no_mailbox_here_by_that_name._vpopmail_(#5.1.1)/maildrop:_error_writi
ng_to_mailbox./maildrop:_signal_0x19/
 <at> 400000003ff925b10cd2a56c status: local 5/10 remote 0/20
 <at> 400000003ff925bb0ce070ac delivery 194019: deferral:
Sorry,_no_mailbox_here_by_that_name._vpopmail_(#5.1.1)/maildrop:_signal_0x19
/
 <at> 400000003ff925bb0ce097bc status: local 4/10 remote 0/20
 <at> 400000003ff925c01c45349c delivery 194020: deferral:
Sorry,_no_mailbox_here_by_that_name._vpopmail_(#5.1.1)/maildrop:_error_writi
ng_to_mailbox./maildrop:_signal_0x19/
 <at> 400000003ff925c01c455bac status: local 3/10 remote 0/20
 <at> 400000003ff925c216fa2de4 delivery 194021: deferral:
Sorry,_no_mailbox_here_by_that_name._vpopmail_(#5.1.1)/maildrop:_error_writi