We can interact with IMAP and POP3 mail servers to retrieve information and messages from them, using the curl command. Also, we can interact with the encrypted channels for those services as well by using the OpenSSL tool.
Interact with IMAP server
curl -k 'imaps://$IP' --user $user:$password -v
Encrypted interaction with POP3
openssl s_client -connect $IP:pop3s
#Once connected we can use the protocol commands
USER $username #Set user
PASS $password #Set password and log in
LIST #List mails available
RETR $index #Get the content of an email
DELE $index #Delete an email from the server
RSET #Reset deletion marks
QUIT #Close connection
Encrypted interaction with IMAP
openssl s_client -connect $IP:imaps
#Once connected we can use the protocol commands
A001 LOGIN $username $password #Log in to server
A002 LIST "" "*" #List all elements in the server
A003 SELECT $servername #Select a mail server to interact with
A005 FETCH $index BODY[] #Get the content of an email
EXPUNGE #Delete or marked emails
QUIT #Close connection
