how dynamically signin to a pop3 email is possible?

Question

I want to know how application like Thunderbird, Outlook can dynamically login a email account (like gmail) only with one username and one password.

Do they keep the famous server login configs (ex: gmail, hotmail, yahoo) in their own database and in login request those info fetchs from their database and merge with username and password for loginning mechanism or there is another mechanism (like requesting to vender email provider for fetching these data) which I don't know ?

Answer 1

Local applications like those normally use local storage (like SQLite or a text file) to store user data. Sometime in plaintext or, better, encrypted.