There's a simple workaround that allows you to create OR filters in Yahoo! Mail, however: two or more filters.
Construct OR Filters in Yahoo! Mail
To create an OR filter in Yahoo! Mail:
- Set up one filter for the first criterion (from a certain sender),
- another for the second criterion (messages with a specific subject),
- and so on.
Make sure all filters move their messages to the same folder and you have constructed an OR filter. All messages from that sender or with the subject (or both) will show up in the target folder automatically.