/service/qmail-send/log: up (pid 1924) 20682 seconds, want down
 

Hi all,
I am responsible for our new qmail server at my work. A few minuets ago some people I work with started complaining about their mail not getting through. So I checked the qmail logs but found nothing. I then ran "qmailctl stat" and this was the output:

[root@my_server]# qmailctl stat
/service/qmail-send: up (pid 2830) 20617 seconds
/service/qmail-send/log: up (pid 1924) 20682 seconds, want down
/service/qmail-smtpd: up (pid 2825) 20618 seconds
/service/qmail-smtpd/log: up (pid 2828) 20618 seconds
/service/qmail-pop3d: up (pid 2831) 20618 seconds
/service/qmail-pop3d/log: up (pid 2829) 20618 seconds
messages in queue: 52
messages in queue but not yet preprocessed: 50

As you can see, all the process are running but the most important one, qmail-send, says "want down" . I then ran "qmailctl restart" and after a couple of minuets all 52 messages in the queue had made it to the users maildir's and everything is back to normal.
This server has been up now for about 3 to 4 weeks without a single problem, I didn't change anything so why did it suddenly fall over??? All I did was boot it up this morning, as usual. I know mail was getting through up till about 9:00am and then, out of the blue, it all came crashing down!
I have googled for an answer but didn't find anything very useful.
It is quite puzzling.

If anyone out there can offer any sort of explanation I would be very grateful.

Thanks