I just sent myself 4 messages in 4 different ways here are my results.

Nokia messaging using my hotmail account - no error message went out from phone but has not showed up in my inbox yet and its been about 3 minutes.

Nokia Messaging using my gmail account - worked perfectly went into my inbox almost instantly

Gmail using the N900 gmail settings for IMAP - worked perfectly only took about 30 seconds or so to show up in my inbox. Failed first time due to my user name being entered wrong in the outbound settings, but after fixing that it worked.

Hotmail using Mail for Exchange - message said sent but I do not see it in my inbox yet and its been about 4 minutes.

I'll update later to say if the MfE and the Hotmail nokia messaging messages ever show up.

Edit: Over 30 minutes later I never got the message from nokia tied to my hotmail address. That is a shame, the mail for exchange message never made it ether but I expected that as I am only use it to sync with a 3rd party server for my calender I dont even remmeber setting up any kind of email service.