MFmailcomposer 's send button is not disabled...?

i am using MFMailcomposer .send button is disabled whe开发者_C百科n "To: " field is empty in simulator. but in device when i run that same application , send button is not disabled...i clicked, "the mail has sent" result has been shown..any help?

In any app I've used with the MailComposer screen the send button is disabled until an address is entered. Looking through the documentation I don't see a way to change the behavior in any way.