We have Exchanges 2003 SP2 on SBS 2003 with GFI MailEsenntials & Mail Security

A major problem has started this week that we cannot track down why its
happening. Basicly the outbound email stops sending email, queues all say
ready or active, sometimes there are queues that say active but have no
messages in them.

I can restart the server and all will be ok again, but it will happen again
usaly within or around 24h from the last time it started. I can restart all
of exhcange but when i try to shutdown the SMTP service it fails to stop or
start again, i think the issue lies there but why i dont know.

Can anyone help with this realy annoying issue.

Fix Outlook Clients Cache Mode
Exchange 2003 and Active Directory Users and Computers.
Multiple people using 1 mailbox HELP !!
OAL (apparently) 0x8004010F
Email rejection