Problem with qmail always get error 554

[giacomob]

After a reboot of the machine the SMTP server doesn.t work anymore.

I always get the same error:
Failed to send data [SMTP: Invalid response code received from server (code: 554, response: mail server permanently rejected message (#5.3.0))].

The qmail log is as following:

May 31 12:07:18 81-31-158-122 qmail-queue-handlers[18388]: starter: submitter[18389] with error code 71
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18388]: mailsend: wait for submitter failed
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18388]: cannot reinject message to mail system
May 31 12:07:19 81-31-158-122 qmail: 1275300438.946987 warning: trouble injecting bounce message, will try later
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18395]: starter: submitter[18396] with error code 71
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18395]: mailsend: wait for submitter failed
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18395]: cannot reinject message to mail system
May 31 12:07:19 81-31-158-122 qmail: 1275300439.112479 warning: trouble injecting bounce message, will try later
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18402]: starter: submitter[18403] with error code 71
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18402]: mailsend: wait for submitter failed
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18402]: cannot reinject message to mail system
May 31 12:07:19 81-31-158-122 qmail: 1275300439.187214 warning: trouble injecting bounce message, will try later
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18409]: starter: submitter[18410] with error code 71
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18409]: mailsend: wait for submitter failed
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18409]: cannot reinject message to mail system
May 31 12:07:19 81-31-158-122 qmail: 1275300439.269250 warning: trouble injecting bounce message, will try later
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18416]: starter: submitter[18417] with error code 71
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18416]: mailsend: wait for submitter failed
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18416]: cannot reinject message to mail system
May 31 12:07:19 81-31-158-122 qmail: 1275300439.294636 warning: trouble injecting bounce message, will try later
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18423]: starter: submitter[18424] with error code 71
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18423]: mailsend: wait for submitter failed
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18423]: cannot reinject message to mail system
May 31 12:07:19 81-31-158-122 qmail: 1275300439.391080 warning: trouble injecting bounce message, will try later
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18430]: starter: submitter[18431] with error code 71
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18430]: mailsend: wait for submitter failed
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18430]: cannot reinject message to mail system
May 31 12:07:19 81-31-158-122 qmail: 1275300439.415000 warning: trouble injecting bounce message, will try later
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18437]: starter: submitter[18438] with error code 71
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18437]: mailsend: wait for submitter failed
May 31 12:07:19 81-31-158-122 qmail-queue-handlers[18437]: cannot reinject message to mail system
May 31 12:07:19 81-31-158-122 qmail: 1275300439.439171 warning: trouble injecting bounce message, will try later

I have tried to apply this solution but it doesn't work:
http://kb.odin.com/836

Any help?
Thank You very much
Giacomo