I know that as of 2 years ago I have not been able to check yahoo pop mail for free with a separate application. A paid account was required. I don't know if took them a while to get to everyone or if they may have batched a hole in their system that is giving you trouble, but you can look for an app called "FreePops", get it, install, then follow any one of many tutorials on how to set it up to check POP access email from yahoo,hotmail, etc.