Please note I receive the exact same error message. A few details:
- Mailserver = Exchange 2007 SP1
- Allow non-provisioned devices is set to True
- Certificate is installed and visible through control panel on N900
- SSL is on (both on server and N900, using port 443)
- Security setting on Exchange server (for Active sync) is set to Basic.

The exact same account and Exchange server works perfectly well with Nokia MfE on my E75 (and E51).

If I can be of any further assistance, please let me know.
Please help!

I would really like for this problem to go away. Exchange has my work e-mail (private mail works fine, using Nokia Mail). And this is vital for this wonderful phone to be a succes.

And happy to report: All other stuff works like magic! It is the most wonderful phone ever. (And it so happens to be our business. In Dutch: www.e-neo.nl. )

Regards,
Jan-Paul