Hello Louis,
Thank you for contacting YesNDR support. Please find bellow inline answers to your questions:
Q: Since I have 3 servers with the Hub Transport role installed, Do I need to purchase 3 licenses of YesNDR?
A: YesNDR should be installed on all servers that accept email messages. If all 3 of your servers accept messages then YesNDR should be installed on all 3 of them and 3 licenses should be used. Processing of messages is done right after the message is received at the HUB/Transport server; if YesNDR is not installed on the specific server then all NDRs passing from this server will not be processed and thus not forwarded to the destination Public Folder.
Q: Do I need to uninstall YesNDR on my 2007 CAS/HUB server before installing on the Exchange 2010 Hub server?
A: No, YesNDR will not affect your co-existence of Exchange Servers in anyway. If you continue to receive messages on your 2007 server then YesNDR should be installed on that server as well.
Q: Do I or should I install YesNDR on each of my new Exchange 2010 Hub Transport role servers?
A: YesNDR should be installed on all “points of entry” of messages on your system. If you have active receive connectors on all of your HUB/Transport servers then YesNDR should be installed on all of them.
Q: Is it true that just installing YesNDR by default settings allows NDRs to go to public folders if the sender address is the address of a Public Folder?
A: Yes this is true. YesNDR will also give you the option to include other system notifications like “Delivery Notifications” or even allow you to include a copy of the message that caused the NDR sent to an administrator.
Please feel free to download a trial version of the software and try it yourself. The documentation includes a step by step installation and configuration process which is very easy to perform.
Please contact us should you need any further assistance with the software.
Best regards,
YesNDR Support Team