I have a Win NT Server running Exchange Server with IP address aa.aa.aa.aa connected to ISP A with domain aa.com and registered at Internic with ns : ns1.aa.aa (for example). We have a plan to move to another ISP, so we install a leased channel to ISP B and I plan to disconnect the ISP A and switch to ISP B.
To make the transition smooth, I install another NIC to the NT server, with IP address bb.bb.bb.bb.

So, right now I have a mail server with 2 IP address aa.aa.aa.aa and bb.bb.bb.bb, the server currently connected to 2 ISP, ISP A & B.
My next step is since I still have a problem to change the ns information at Internic, I ask the ISP B to query my domain aa.com to their dns and MX Record for aa.com to be pointed to bb.bb.bb.bb.

My opinion right now is : No matter the mail come from aa.aa.aa.aa or bb.bb.bb.bb the mail will reach my mail server.
But somehow, probelm occurs, I cannot receive email sent from bb.bb.bb.bb, but if from aa.aa.aa.aa is ok.
another information, I did not make any changes at the Exchange Server.

My question is, why I can not receive email sent from IP bb.bb.bb.bb, because if we think logically, the mail sent through bb.bb.bb.bb will also go in to my mail server also right? Could anyone please give me any suggestion about this, because right now, I still confuse and I still haven't find any way out.


alpokat