Multiple accounts are used to check for messages from more than one email address
and/or mail server. Select Settings->Configure KMail... and click on the
Network page to add or change your account settings. See the
Getting started section for more
information on the settings in the Network page.
To check for messages from a particular account, use the
File->Check Mail
In submenu to select the account to check
for mail. You can also press the mouse button on the Check
Mail icon for some time to get a list of accounts.