Clicked on preview - No SEND button?

If you have clicked on preview - and there is no send button - then you have forgotten to put in a subject or to add any recipients. There should be a message at the top of your screen that says: "No recipients to send to" or "No subject" or both - and the Back to compose button. Click on the Back to Compose button - which will take you back to the Compose screen - and add a subject and / or recipients - then click on Preview again. The send button will now be there.