I've found an info from Yahoo regarding stationery. Unfortunately, it is being removed because the feature wasn't popular according to their data. GIFs are also affected.
If you still have stationery right now, it will be removed soon...
Same here.....I can't get it to return. Yahoo wants $$$ for help - can't write them. Loyal customer for years.
I confirm that stationery is still available in Yahoo Mail. Try logging out of your account, clear your web browser's cache and cookies and log back in.
If it doesn't come back, make sure your web browser is on the latest version or try another one. Check also that you're using New Mail (stationery isn't available on Basic Mail) - if you see a link "Switch to the newest Yahoo Mail" in the menu bar, click on it.