The Domino server POP3 Collect addin shows the error
«Date/Time» POP3 Collect: «Connection Name» - Unable to read messages from POP3 server «POP3 Host Name» - Account «Account Name»: Connect failed
The POP3 Collect addin Java task is unable to establish a connection to the configured POP3 server.
Check if the Domino server running the POP3 Collect task is able to connect to the POP3 server. This can be done by executing the «telnet» command at the Domino server, e.g.
telnet pop-mail.outlook.com 995 Trying 18.104.22.168... Connected to pop3.glbdns2.microsoft.com. Escape character is '^]'. Connection closed by foreign host.
If you get a «Connected to» message, the Domino server is able to establish a TCP/IP connection to the configured POP3 server at the specified port. If not, check you network for any firewall rules which may prohibit the connection.
If the POP3 connection is using SSL, check if the root certificate authority (Root CA), who has signed the SSL certificate on the POP3 server is present in the Domino Java Virtual Machine (JVM) keystore. To display the used SSL certificate, see the link below. The distributed JVM keystore only contains a small number of trusted root CAs, but you may add any missing root CAs to it (see below).