SELECT * FROM MailMessage A
WHERE id in
(SELECT TOP 1 id FROM MailMessage
WHERE A.Mfromid = Mfromid ORDER BY MsendTime DESC
) and Mtoid=3
SELECT * FROM MailMessage A
WHERE id in
(SELECT TOP 1 id FROM MailMessage
WHERE A.Mfromid = Mfromid ORDER BY MsendTime DESC
) and Mtoid=3