Sometimes images may look blurry on some screens if the size of the image is too small or too big. Therefore, it's recommended to amend the image resolution, keeping the resolution 2x higher than the image's size in the signature itself.
It is strongly recommended to use a high-quality image, and what's more important, the image's resolution should be divisible by 2, 5, and 10. For example, 200x200 or any other round numbers.
We recommend uploading an image with a high resolution and high DPI (300). For example, if your logo appears as a 150x150 image in the signature, then a 450x450 image has to be uploaded.
Advisable PNG format.