Your message is large because you're sending the photo along with it.
The small ones reference an image stored on a web server. You need to
post your images on a web server and make your footer reference it.

Gregorio Aranda wrote:

Hi everyone,

I want to make a footer with my address and phone number including a small
logo picture of our business. The trouble is that when I tried, this use too
much space (nearly 40 kb.) when I sent the email. I have mails on my inbox
that is a full image and the size is not bigger than 9 kb. (including text
and everything). What should I do???

Greetings,
GA