Unable to connect to POP3

The other day I was troubleshooting an issue where a couple of business applications could not connect to their mailbox using POP3.

First, I made sure that both POP3 services were running across all servers., Then, I enabled POP3 logging by running the following cmdlet:

Set-PopSettings -Server “server_name” -ProtocolLogEnabled $True

And restarted the POP3 service. However, I couldn’t find anything in the logs...

So, I turned to telnet. Using this great tool and by connecting to one particular server, everything seems to be working fine. However, when connecting to another server, I would not get the usual banner, but only a blank screen! OK, definitely something not right with POP3...

It turns out this issue was occurring because the PopProxy component was in Inactive state for this particular server! I found this by running the following cmdlet:

Get-ServerComponentState “server_name” -Component PopProxy

We can use the following cmdlet to determine which requester made PopProxy inactive:

Get-ServerComponentState “server_name” -Component PopProxy).LocalStates

In my case, the requester was HealthAPI that changed the state of PopProxy to Inactive. As such, in order to bring it back to an Active state, all we have to do is run:

Set-ServerComponentState “server_name” -Component PopProxy -State Active -Requester HealthAPI

And all is back to normal! :)