I am attempting to set up My Email Settings with the HTML signature, so that our company logo will display when an email is sent to a contact list. I have been attempting to set the <img> tag as directed via the salesforce support documents, but it fails every time and returns the text version of the link. 

I am currently using the following syntax:

<img src="https://na174.salesforce.com/sfc/p/6g0000023Nda/a/6g000000Kzfv/qF8bdtm457gt5A7ot8tDpx22GEUUF7oafuZO5xq.PhY"/>

However its simply displaying the "?" where an image should be. 

Any and all help in getting the image to show up would be appreciated. 

Thank you

Pete