Thanks for taking the time to share this with us. If possible, could you let us know if you experience this issue on the desktop version of Mail too?
An error occurred while saving the commentleonard nathan commented
All the comments below tell the same story: No matter what filters one puts in place, no matter how many times one flags an email and/or marks it as spam - you get it again.
Seems the only real way out is to stop using yahoo email.
If enough of us do that, something tells me the filters, and Yahoo! Mail, would improve quite quickly.