Exchange 2013 – Setup POP3 Service via CAS Servers

Microsoft Exchange

If you’re like us you still have old legacy applications that use POP3 for various things. On Exchange 2013 the way POP3 works has changed slightly. Now you access a POP3 mailbox via the CAS servers that proxy you to the mailbox on the Mailbox role server(s).

Our application only supports plain text authentication, but this unsurprisingly is disabled by default, to enable POP3 and turn on plain text authentication follow these steps below. Note in my setup we have two CAS Role servers and two Mailbox Role servers.

1. Start the Microsoft Exchange POP3 services on each of the CAS Array servers. And the POP3 back end services on the Mailbox servers.

2. Set it to Automatic start for all these services.

3. Then on the EAC, go to the “Servers”, then click the “Servers” tab at the top. Now for both the CAS servers you need to do the following:

3.1. Click on the CAS Server, click on the edit button (pencil).

3.2. Click on the “POP3” option on the left hand side.

3.3. Set “Logon Method” to “Basic Authentication (Plain Text)”.

3.4. Repeat for all the other CAS servers, then restart the POP3 service on all the CAS servers and Mailbox servers. Then you are ready to test.

4. To test it is working telnet to the CAS array DNS name on port 110. And attempt to login by running the commands as below:

+OK The Microsoft Exchange POP3 service is ready.

USER username


PASS password

+OK User successfully logged on.


+OK 8 31602

1 4017

2 4009

3 4013

4 3521

5 3995

6 4004

7 4016

8 4027


5. Now repoint your applications to use the CAS array DNS name on the Exchange 2013 infrastructure.

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