Add some inline images and a bunch of layout and you can easily hit that.

And yes I'm happy to argue about the evils of HTML in email and how I can't read your email in pine, just like I was in 1997. And I'd still lose the argument just like I did back then.

Not only table styling, as another person said. Duplicate CSS also.

I've done view source on some newsletters. On at least one there is a top-level CSS style block with all of the rules. Then, who knows why, there's a duplicate of every single rule placed inline to the table row TR tags.

That one also has zero line breaks and exceeds 1,000 characters per line (an SMTP violation). Unlike some other newsletters that bounce off my mail server, this one's sending script "fixes" it by arbitrarily adding a line break at 998 characters no matter what word is at that position.

I've sent them links to the RFC and notes about the broken rendering but they just don't care.

Yes. If an email is bigger than 102KB (excluding attachments), there's a 99% that I don't want it.

View source on any "designed" emails you get. You will see a LOT of <table> related code. You can easily end up with a 10:1 ratio of HTML to content with the more elaborate emails.