NSTimeInterval oneHour = 3600;
 NSDate *now = [NSDate dateWithTimeIntervalSinceNow:oneHour];
 MCOIMAPSearchExpression * exprSinceLastTime = [MCOIMAPSearchExpression searchSinceReceivedDate:now];


MCOIMAPSearchExpression * exprFrom = [MCOIMAPSearchExpression searchFrom: @"apple"];
MCOIMAPSearchExpression * exprSubject = [MCOIMAPSearchExpression searchSubject: @"cloudkit"];
MCOIMAPSearchExpression * expr = [MCOIMAPSearchExpression searchAnd: exprFrom other: exprSubject];

MCOIMAPSearchOperation* searchOperation = [session searchExpressionOperationWithFolder: folder expression: expr];