var msgs = imap.SearchMessages(
         SearchCondition.From("no-reply@mydomain.com").And(
            SearchCondition.SentSince(new DateTime(year, month, day))
        ));

var msgs = imap.SearchMessages(
               SearchCondition.From("no-reply@mydomain.com")
                );

 var msgs = imap.SearchMessages(
               SearchCondition.SentSince(new DateTime(year, month, day))
                );

xm005 UID SEARCH (FROM "no-reply@mydomain.com") (SENTSINCE 11-Sep-2012)