If you ever receive the error:

Error: 500 Failed to connect with the search service

when trying to connect to GFI MailArchiver, and in the event log an error about cannot find an IPC file, the reason is most probably a port conflict on port 8019. In my case Intuit QuickBooks had a service running called QBCFMonitorService.exe and that was listening on the same port. Stopping the QB service and marking it as disabled, then restarting the GFI MailArchiver Search Service fixed it for me.

Update: There is a better solution that I ended up implementing, because I needed to run QuickBooks on the same machine. Here:

"ianb - What you would need to do is to open (using a text editor) the exe.config files found in the bin directory and change any ports that refer to 8019 to the new port. This needs to be done for all services.

Also you would need to modify ASPNETremoting.config and change the same port to refer to the new port. "

Also do an iisreset afterwards. Here is the thread.