The following run locally on the VPS also produces 0 messages from list
[root@xxx certs]# telnet mydomain.com pop3
Trying XXX.95.10.XXX…
Connected to mydomain.com.
Escape character is ‘^]’.
+OK Dovecot ready.
user catchall.xxx
+OK
pass thepassword
+OK Logged in.
list
+OK 0 messages: