Apps How to read all Email and Gmail programmatically

[websurf]

Hello, Guys,
I need to read all Email and Gmail, then remove the specific one(s). But I found Android doesn't provide APIs to receive Email, and I read Gmail failed as following:
ContentResolver resolver = getContentResolver();
Uri uriGmail = Uri.parse("content://gmail/");
Cursor cursor = resolver.query(uriGmail, null, null, null, null);
.................
function resolver.query(xxx) returns null;

how can I implement those features? Thanks a lot.