Srv 2003 SP1 / Exchange 2003 SP2 / Windows mobile V5

Hi

I have 3 clients with Windows Mobile V5.
OMA Setup is OK, I can synchronise with exchange , so Direct Puch send /
receive is OK, but I can receive the mail ONLY when clients PC with Outlook
2003 is open.
If outlook is closed I can send the mail from mobile but can not receive the
mails or calendar/contact/task update.

I made the test on 2 diffrents Exchange 2003 SP2 (branch office) but the
result is the same.

Any idea?

(I'm sorry but crossposting do not work on my IE6)