Sending email?

Is there a way to find out what my default email is? If I send an email thru messages, it gives me the option to change from default to a different email account. But I can't figure out which account is set as the default. Is that not something I can change?

From the main screen go to:
- Options
- Advanced Options
- Default Services

And change the default service (CMIME) to whatever email address you want as default.

Thank you! That was very helpful. :)