Use the below code to send a file within a email.
String filename="contacts_sid.vcf";
File filelocation = new File(Environment.getExternalStorageDirectory().getAbsolutePath(), filename);
Uri path = Uri.fromFile(filelocation);
Intent emailIntent = new Intent(Intent.ACTION_SEND);
// set the type to 'email'
emailIntent .setType("vnd.android.cursor.dir/email");
String to[] = {"[email protected]"};
emailIntent .putExtra(Intent.EXTRA_EMAIL, to);
// the attachment
emailIntent .putExtra(Intent.EXTRA_STREAM, path);
// the mail subject
emailIntent .putExtra(Intent.EXTRA_SUBJECT, "Subject");
startActivity(Intent.createChooser(emailIntent , "Send email..."));