Just an FYI

The way I had to set it up was as follows
go to email.nokia.com and create a new acct. (do this by entering your email acct "yourname@gmail.com" and enter the password for that email acct.)
Once you do that you proceed to your n900 device and click on the email Aplication
click on mail(in the title bar) and select new acct
choose next
and where it says region, choose your region (mine was USA)
under service provider select Nokia Messaging from the drop down box
then choose next
Enter your email address and password, (the one you used @ email.nokia.com to create an acct)
then choose next

I believe after that evrything will sync(there are some settings you can change about syncing preferences)
to add other email accts, go back to email.nokia.com and log in (if your not already) and choose add another under "My Email Address" and follow prompts