Composing new emails
You can compose a reply to an email you have received but unfortuanately we don't support composing a new email.
The reason is that we don't have access to the phone's address book name recognition. We can request permission to the phone address book but unfortunately cannot do voice recognition against it. Our voice recognition is only common first names and real words, but some people have unusual names and this is a very different challenge.
If you are on iPhone we recommend asking Siri to compose new emails, which is the only email related thing Siri is good at :)
So if you hold down home button (or other trigger for Siri) then say "compose email". If you have voiceover on Siri reads the options to you (very helpful, normally it doesn't bother). Then tell Siri "open speaking email" to get back.