Setting GMail to import all your Yahoo (bellsouth, att, etc) email to GMail

1. Click on the gear on the right side of your mail Gmail screen.  (Must be in your Gmail screen! not some other screen.)
2. Click on "Accounts and Import"
3. In the area that says "Check mail from other accounts," click on "Add a POP3 mail account you own".  The first pop up screen asks for the "from email" address.  Click "Next Step"
4. In the resulting popup screen, which is the above picture, enter the email address of the Yahoo account, including the domain (eg, @bellsouth.net).
5. Enter the password
6. The server name is "inbound.att.net"
7. The Port is 995
8. Make sure the box that is labeled "Always use secure connection..." is checked.
9. The other check boxes are up to you. 
1. Leave a copy...:  if this box is checked, mail will remain on the source server.  That server's email account will fill up over time and become a problem  I recommend not checking this box.  When not checked, every email that is copied to gmail is deleted on the source account.
2. Label incoming messages...: if this box is checked, all the transferred messages will be put in a mail folder of the name you provide.  This might be useful if you have had a gmail account and have duplicate emails in both accounts.  In that case, you can review the first batch of transferred emails for non-duplicates and pull them out of this folder, then edit your settings to remove the checkbox and delete the folder.  But this is usually too complicated:  just leave the box unchecked.
3. Archive incoming messages... If this box is checked, then the transferred emails do not go into your Gmail inbox, they just go into your email account.  The way to get to them is to click the "All mail" "folder" on the left hand navigator of the Gmail page.  It is easiest to not check this.
10. Click "Add Account"