With Google's Mail Fetcher utility, you can forward Yahoo email to your Gmail Inbox even if you don't have a paid Yahoo Ad Free Mail account. Once Mail Fetcher has your account information, it can sign in to your Yahoo account and begin transferring messages to Gmail. Technically, Mail Fetcher does not forward your mail, but uses the POP3 or Post Office Protocol version 3 protocol which requires messages on Yahoo's server be deleted after they are sent. Mail Fetcher provides an option, however, that overrides POP3 and leaves mail as is in your Yahoo Inbox.

Configure Gmail Transfer Yahoo Messages

Use the Account tab of Gmail's Settings tool to add Yahoo Mail as a POP3 email account. Enter your Yahoo credentials and then follow Gmail's prompts to complete the setup process. Mail Fetcher will begin transferring your Yahoo email to your Gmail Inbox. Some Yahoo messages, however, may go straight to your Gmail Spam folder instead. If you like, you can create a unique label for the messages sent to your Yahoo email address that will enable you to view them in a separate category from those sent to your Gmail address.