Signature in Yahoo Mail, appended to all your outgoing emails. You can make liberal use of all the rich text formatting tools available, but you cannot add images to your signature when using this method.
You can insert pictures into your messages manually, but if you want to use a picture as your email signature so that it shows up each time you send emails, you have to use another way to do it.
How to insert image into signature in simple Yahoo Mail
Steps 1: Open and Sign in Yahoo Mail. Click or tap the Settings gear next to your name at the top of the screen.
Steps 2: Choose Settings
Steps 3: Go to the Accounts. Choose your email address under the Email addresses section.
Steps 4: Type your name and any other text that will be part of the signature.
Steps 5: Photo you use in your signature must be uploaded and accessible at an online hosting website. Upload it to a site such as Imgur or one of the many other hosting sites.
Note: The image should be small to look right at the bottom of an email. If it is large, you need to resize it so that it fits.
Steps 6: Position the cursor in the signature box where you want the image to appear. Right-click and select “Paste” to place the image in the signature box.
Steps 7: Choose the Save button when you’ve finished with the signature. Open a new email in Yahoo to view the email signature.
With the steps above you can insert images into the signature in Yahoo Mail simply, so you can make a difference in your Yahoo Mail, wish you success!