How Extras work in Mail Application in Android

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http://stackoverflow.com – I am creating my Android Email App which has subject ,message and recispient field. Intent emailintent= new Intent(android.content.Intent.ACTION_SEND); emailintent.putExtra(android.content.Intent.EXTRA_EMAIL, emailAddresses); emailintent.putExtra(android.content.Intent.EXTRA_SUBJECT, "This is a Subject"); emailintent.setType("plain/text"); emailintent.putExtra(android.content.Intent.EXTRA_TEXT, message); startActivity(emailintent); Now i understood Action_SEND is an action and Mimetype is "plain/text" and mail app will catch this filter. but how does EXTRA_EMAIL,EXTRA_S (HowTos)