Dear All, We have 1 email server , and ISP help us setup relay email Our MX 10 ISP MX 20 Now, we suffer two problem, First, we dont understand why some mail will pass throught ISP mail server and then pass to us. Second, the ISP mail server will reject mail if the send mailer cannot reserve dns After reject, it seems not retry anymore. Does any have any ideas? Thanks

Rejecting mail from an MX that doesn't resolve reverse DNS is pretty standard practice. Maybe your ISP can turn it off just for you, but i doubt it. Either way, give them a call on the issue. Mail would route to your ISP then your mail server if your inet connection was clogged/down or your server was too busy to accept the connection.

How can I measure the Email server is busy? Because I didnt see the loghave reject email