Your mail managing program can receive, literally, hundreds of accounts.

However, for the freebie setups, such as one that you use for signing up on some website, forum, etc.

Most will simply leave those as web based and not tie them into their mail management software.

For example, to check your various hotmail accounts ... simply "hotmail.com" and sign in.

Then, sign out and check another and another and another.

The same can be said about gmail, yahoo, etc.