Have you sent your email signature from your iPhone to Mac (Apple) Mail and detected that it's too small?
When using a signature template with significant elements such as a fixed width table or a large banner, your iPhone may re-sized your signature to "Fit Screen". This happens because some mobile devices are designed to reduce the entire email's content to fit onto the screen, and the corresponding changes are saved when you open the signature on the MacBook.
When opening an email, you may see that the content will jump from a standard reading size to a much smaller size. This is because the email being sent has an element more significant than the device's screen size, and the mobile device will reduce the whole email to fit on the screen. Unfortunately, this is a device-specific setting and cannot be changed or influenced by the signature design.
To prevent this from happening, please follow all the steps from the guide on how to install the signature on iPhone/iPad.
Try keeping the signature width to 450px depending on the most extended piece of information, and set any disclaimers to wrap. Check that the signature images are also re-sized using an image editor to their correct width and height required for the template.
Please note that we recommend uploading an image with a high resolution and DPI (300). For example, if your logo appears as a 150x150 image in the signature, then a 450x450 image must be uploaded. Advisable PNG format.