Yahoo Mail

Add your signature

1. Copy your signature from Sigxel.
2. Open Yahoo Mail in a desktop browser.
3. In the new interface, choose More options → Settings → Writing email. In the classic interface, choose Settings → More Settings → Writing email.
4. Enable the signature toggle for the email address you use.
5. Paste into the editor. Compose a message and check the result.

Repeat for each address if you use multiple mailboxes. The mobile app has separate settings, so check it independently. If formatting changes, try a simpler template and send a test message.

Source: Yahoo's signature settings guide.