This is my 12.12.21 review update for those who've commented about the Contacts and Calendar panels being blank when you click the icons. A workaround is to launch the gear icon mail settings, click "More settings" and then click "<— Back to Inbox". The Contacts and Calendar panels should show up now when their icons are clicked. Works for attachment previews too.

As me2 wrote three months ago:
"This addon (v3.60) breaks some features of yahoo mail.
When I click on contacts or calendar icons, the panel opens but it is completely blank.
The same happens if i try to preview an attachment (images, docs, etc)."

Up until FF upgraded 93.0 (64-bit) with both Win-10 & 7 (on PC), this has been a 5-star rating. It actually still is. Grateful and thankful for the author's work on this.
Currently I would consider this a broken app, because yahoo has found a way to push their right side ads again. The screen is being occupied by their garbage again.
They have also been able to temporarily push their small ad area above the subject lines (shows up for a few seconds, then goes away).
This has been an exemplary program. I am hoping that the author can find a way to smack down yahoo again.

This addon (v3.60) breaks some features of yahoo mail.
When i click on contacts or calendar icons, the panel opens but it is completely blank.
The same happens if i try to preview an attachment (images, docs, etc).

Super extension ! Mais il y aurait une amélioration à faire : supprimer l'affichage de 2 vidéos, une dans les "Spams" et l'autre dans la "Corbeille". Là ça serait parfait ! Merci d'avance

很好！世界變得乾淨了！ :)

Yahoo Mail Hide Ad Panel used to block all the ads; nowadays Yahoo has managed to get the top "sponsored" ad to poke through. It does successfully block the left- and right-side ads that waste so much screen real estate. Thank you so much, Piyush! Hopefully you can find a way to block the extremely annoying top sponsored ad, too.

Unfortunately, it breaks core functionalities of yahoo mail.
I think this extension is too aggressive!
Indeed, it does hide the panel at the right, but however,
this panel is used also to show contacts, calendar and
previews.
After installing this extension, the right panel is always
blank when you open it, regardless of the content it should
display, not only ads!
This means you can't see your contacts or your calendar and
also, you can't preview an image or document from email
attachments.

This extension does NOT block the sponsored ad that Yahoo places at the top of the list of e-mails in the Inbox. Please let me know of any extension that blocks Yahoo's ad at the top of the list of e-mails.

Works fine left and right, but the one in the centre top remains and does not go away, despite uninstalling and reinstalling the extension. No idea why this is the case...

Nevertheless, big thanks to the author!

Small & perfect! People claiming to have problems should check if other add-ons are conflicting.

works on left and right side but since yahoo has been cracking down and forcing you to refresh the page to see your email every time you click on something, the center ad at the top of the inbox is still showing with this add-on

Just started using it, but am LOVING it! Thank you SO much for taking away that annoying side panel!! Thank you!!

This add on has not been updated for over a year now. It used to work great but not anymore.

It needs just a small refinement, to become perfect.
Currently, the problem is that it breaks the preview functionality.
When a message has a document or a picture as an attachment, if i click "Preview",
the pane for preview appears at the right of message's body but it's blank.

[Edit]
Unfortunately, things are even worse..
It breaks also the "Contacts" functionality. When i click the "Contacts" button at the top-right,
the right side expands towards the left, but it's also blank. So, it's not possible to see my
contacts, edit, add, delete, etc.
If i disable this extension, both of these issues get gone.

good

Well, the addon did not work for me, I am using version 66, installed with no issue but made no change at all to that annoying ad that is placed at the top of the email inbox page......we missing something??