Yahoo!'s automatic settings leave the messages in the Inbox of your external mail account. However, you can choose for them to be deleted from that Inbox if you want.

To set Yahoo! Mail to delete the mail in your other account's Inbox after bringing it into Yahoo! Mail:

1. Click Options in the upper-right of your Yahoo! Mail page and select Mail Options.
2. From the list on the left, click Accounts.
3. Click Add or edit an account.
4. Click once on the account you want to change the settings for. Then click Edit.
5. Find the "Leave Mail on POP server" setting. It's in the last category, "Options." Click the box to add or remove the "check."
• Check the box to keep the messages in the Inbox of the other account.
• Remove the check from the box to delete them from the other account's Inbox.

Done? Be sure to click the Save Changes button in the lower-left to put your new settings into effect.