In the latest version of Mac X mail, you can add an image to your signature(s) easily.
1. Open Mac Mail and go to Mail -> Preferences -> Signatures
2. Click + to add a new signature template.
3. Next, find the image you want to place inside your signature. Simply drag the image into the signature white space screen pictured below.
4. The image will automatically resize to fit in your signature. You can still resize the image by dragging the corners.
Create a Clickable Image to Link to Another Website
1. Open Mac X Mail and create a new signature
2. Drag any image into your signature you want to create a hyperlink to.
3. Select the image in your signature and go to Edit Menu -> Add Link
4. Send yourself an email with the new signature you created. Your image will be a clickable link.
1. Create a new email message.
2. Copy your image into the new email message. Ensure only the image is placed in the email (no other text)
3. Now, select the image (ctrl + a) and go to Edit Menu -> Add Link and type in the web address you want the image to link to.
4. Finally, ensure you still have the image highlighted (ctrl +a) and copy the image (ctrl +c). You can safely close this mail message without saving it.
5. Go back to Mail -> Preferences -> Signatures and paste (ctrl +v) the image into your signature. Done!
You can test your new clickable image in your signature by sending yourself an email and hovering over the picture once you receive it – it should click away!