Gmail and others – but primarily Gmail take note of the percentage of the content of any “bulk” email that is an image/s (bulk being the category all ESPs have to label emails with in the email headers)
If image/s represent more than 18/20% of the total email it is taken as being indicative of Spam as many Spammers use images to camouflage spammy text.
Gmail have another nasty feature we all need to avoid – any emails with more than 18% image/s are “clipped” – i.e. only a part of the email is displayed, usually just the first two or so lines of text, by default and the recipient has to click on “see more” to see the remainder of the email – obviously not a desirable situation.
That means this page sent as an email would probably fail the test, the size of the logo image would need reducing by maybe 50%!