POP3 mail servers may support different capabilities defined in RFC 2449. Using a pop3
command, we can list them, and thanks to Nmap, we can automate this task and include this service information in our scan results.
This recipe will teach you how to list the capabilities of a POP3 mail server with Nmap.
Open your favorite terminal and enter the following Nmap command:
$ nmap -p110 --script pop3-capabilities <target>
A list of server capabilities will be included in the script output section:
PORT STATE SERVICE
110/tcp open pop3
|_pop3-capabilities: USER CAPAUIDL TOP OK(K) RESP-CODES PIPELINING
STLSSASL(PLAIN LOGIN)