While trouble shooting on plesk servers on email issues..
there is no need for asking for password from the client.

It is that plesk saves the password in mysql database
just we have to pull the data out of the database.

As administrators login as root are aware of getting the plesk password.

#cat /etc/psa/.psa shadow
will have the password.

login to mysql as admin or root

mysql -u admin -p
password *****

mysql> use psa;//selecting the psa database//

mysql>SELECT accounts.id, mail.mail_name, accounts.password, domains.name FROM domains LEFT JOIN mail ON domains.id = mail.dom_id LEFT JOIN accounts ON mail.account_id = accounts.id;

That's it all the (email accounts in the server + password + domain ) will be displayed ....so there is no need to ask for the password for the email account in the server..