I am replacingour Exchange server with a new updated system. Current setupis using a firewall SMTP proxie that forwards e-mail to the IP address of the current Exchange server.After I move mailboxes from the old server to the new server, it will be necessary to change the IP address to which mail is being forwarded to that of the new server. What will happen to mail that is forwarded to the old server that no longer host mailboxes beforeI am able to change the forwarding address on the SMTP proxie to that of the new server? Thank You

The mails which was forwarded to the old server where the mailbox not exist - in this case the sender will be getting NDR. you cant find those message. In such kind of scenarios while moving the mailbox from one server to another is - You need to add the multiple port forwarding in the Firewall. Thanks and Regards,Ashwini Kumar

It depends. When you're placing a new Exchange Server in the same Exchange Organization and thus in the same Active Directory domain as the old Exchange Server, your messages will be forwarded to the moved Exchange mailboxes without problems,as long as you're not using any smart hosts on your virtual SMTP servers. (use Send Connectors) In any other scenario's you might encounter non-delivered and/or delayed messages, as Ashwini describes Please also note: Outlook settings Migrating this way will also ensure you don't have to change any Outlook settings too. Their configurations will be addressing the old Exchange server, which knows the new mailbox location. As long as the old Exchange server is in place Outlook configurations will be changed automatically to point to the new Exchange Server. Once everyone (or a sufficient number of users) have logged on you can remove the old Exchange Server appropriately. Outlook Web Acess, etc You will get in trouble with Outlook Web Access, Outlook Mobile Access and Outlook RPC over HTTP(s) though, when you're forwarding ports 80 and/or 443 to your Exchange Server. The best way to tackle this is to communicate the functionality is unavailable during migration time. Port forwardings Change the port forwarding rulesfor incoming ports 80, 443 and 25 when you've moved all your mailboxes. (depending on the size of your store this might take a long time). Don't forget to change any specific outbound rules as well. Good luck!

Gentleman: Thank you for the information.