If you retrieve messages using MercuryD and Mercury logs show no incoming connections at all it could be that the Windows firewall on the server is blocking access. If that's not the case you could try establishing a connection to the server with Telnet to see what happens. To connect using SMTP (port 25) open a command window and enter telnet mailserver 25 (replace "mailserver" with the IP address of the server). 

I've been using Mercury for some years now. It's been installed on an old Windows 7 laptop which has performed the job of mail and print server quite adequately. A few days ago the laptop died, so I decided to copy the Mercury installation over to another old Win 7 desktop machine to distribute our emails until I get the laptop sorted.

I've copied the installation like this before and had no problems with it, but this time, when I try to check emails from my client machines, I get "No response from server" on my clients (Using Forte Agent). Nothing else has changed.

My mail server has a fixed IP on the network, and I've checked that this is correct. I can ping the mailserver from clients and vice versa, I can see the drives on other computers in both directions, so my network appears to be working normally. The clients are running Win10 and are part of the same Homegroup. There is no domain.

Mercury is definitely running and is successfully retrieving messages, but I just can't get it to talk to the clients. This has never been an issue before. 

 Any thoughts?