You can add multiple accounts, but Windows Mail doesn't have identities or a
password option....
Windows Mail puts email from all accounts into the same Inbox, and there's
no setting to change that.  When you send a message, you can select which
account to send from, by clicking on the From: box.

Here are a few alternatives...

1.  Create folders for each email account and create message rules to move
email addressed to each account into the appropriate folder.

2.  Create and use different Windows Users, each with WM accessing only
their email account. (This is how you set a password to keep other users
out.)

3. Use the newer Windows Live Mail which has separate folders for each
account, but no identities or password:
http://get.live.com/wlmail/overview

4. Purchase WMIDs which adds identities to WM
http://www.oehelp.com/WMIDs/Default.aspx

Five possibilities:

1.  Use different Windows Users

2.  Make new folders and make a message rule like this:

Apply this rule after the message arrives
Where the message is from the mail.fjsmjs.com account
Move it to the fjsmjs folder
   and Stop processing more rules

3. Use Windows Live Mail which has separate folders for each account:
http://get.live.com/wlmail/overview

4. Buy WMIDs  http://www.oehelp.com/WMIDs/Default.aspx

5. Enable the Account column in the Inbox.