Question : Problem: Error 0x80070900 when using SSL for ActiveSync or OMA to our Exchange Server

I get Error 0x80070900 when using SSL for ActiveSync or OMA to our Exchange Server with any Windows Mobile device I try (but main one I am testing with is  Windows Mobile 6 Pro.

Answer : Problem: Error 0x80070900 when using SSL for ActiveSync or OMA to our Exchange Server

Is the Exchange 2003 Server an SBS server?  If it is, then this article will not be applicable to your issue and should not be done.  Rerun the SBS CEICW and this will create the Exchange-OMA virtual directory.  you may also have an issue with the SSL certificate.  Are you using a commercial certificate or a self signed certificate?   If it is self signed, you need to install the certificate onto the phones.  If it is a commercial certificate, you ma need to obtain an intermediate certificate from the provider and install onto your server.  

More info on Exchange 2003 ActiveSync:

http://www.amset.info/exchange/mobile.asp
http://www.amset.info/pocketpc/certificates.asp