This is only good for yahoo mail plus...
Configuring External (POP) Mail Accounts in Yahoo! Mail
With Yahoo! Mail Plus, you can retrieve messages from most external email accounts. Outlook, Eudora, or Netscape Mail inboxes are all accessible from Yahoo! Mail Plus after following the brief set-up procedure below.
To complete the process, you'll need to find out the mail server name for each account you wish to add. You can get this information by talking to either the Internet Service Provider you use to connect to the Internet, or the Network Administrator who controls the system at your work or school. Verify with them that it's a POP server, as only POP servers are supported at this time.
Yahoo! Mail Plus can store settings for up to 5 different accounts at one time. You can either add an account with Yahoo! Mail's automatic delivery settings (1.), or you can add an account and manually set the delivery options yourself (2.).
To add an account:
Click the "Options" link at the top right of your Mail page to open Options.
In the "Management" column, click the first link – "Mail Addresses".
On the page that opens, Mail Accounts, click the "Add" button.
Enter an account name. For example, "Work", "School", etc. Then either click "Continue" on the lower left, or hit "Enter".
Enter your mail server name – the info you got from your Internet Service Provider or Network Administrator.
Enter the user name and password for that account. Please note: The user name is different than the full email address. Typically it is the text before the "@" symbol in your email address. Your password is whatever you use to access that email account – not necessarily your Yahoo! password.
Select an indicator color to mark messages received from this account.
Click the "Add Account" button. Your account is now added!
To add an account and manually select delivery options:
Click the "Options" link at the top right of your Mail page
In the "Management" column, click the first link – "Mail Addresses".
On the page that opens, click the "Add" button.
In the upper-right corner of the page, click the "Configure Account Manually" link.
Enter an account name. For example, "Work", "School", etc.
Enter your mail server name (only POP mail servers are supported at this time).
Enter the user name and password for that account. Please note: The user name is different than the full email address. Typically it is the text before the "@" symbol in your email address. Your password is whatever you use to access that email account – not necessarily your Yahoo! password.
Select an indicator color to mark messages received from this account.
In "Deliver To:", choose a folder to route incoming messages from this account.
In "Options", check (or don't check) the boxes next to the following:
Override default POP port - If you know your POP server uses a port other than 110, enter the port number here. Note: For assistance tracking down this information, contact your Internet Service Provider or network administrator.
Leave mail on POP server - Specify whether messages retrieved to your Yahoo! account will also remain in your external mail account, or whether you want them deleted from your external mail server.
Retrieve new messages only - Specify whether Yahoo! Mail retrieves only the new messages in your external mail account, or all messages.
Use filters - Checking this box applies Yahoo! Mail's filters to incoming external mail.
Click the "Add Account" button. Your account is now added.
Currently, you can't configure Yahoo! Mail to retrieve messages from web-based email accounts like RocketMail or another Yahoo! Mail account that has been set up for POP access.
To retrieve your messages from an external mail account, click the appropriate server name on the left-hand navigation bar (you may also check your external mail account(s) by clicking on the "Check Other Mail" link on the left-hand navigation bar). Messages from the selected server will be retrieved to your Yahoo! Mail Plus account.
Yahoo! Mail Plus will retrieve messages from your external (POP) mail accounts only when you request it.
In addition to receiving messages from your external mail accounts, you can also send messages from those accounts. When you write a message, just select the "From" email address you want to use.