Give people HTML and most e-mails will be a complete undecipherable garbage on the markup level.
Basically almost everyone puts anything there so that they get some visually pleasing result, the markup semantics be damned.
One would think that lack of features of various mail clients would lead to using the lowest common denominator of some basic tags like b, i, a, hr, and maybe img.
Not so in reality.
One bank I've seen e-mails from even abuses invalid parsing of HTML comments, to produce whatever insane result someone somewhere dreamed up, like this:
<!--><div style="some:crap"><!-->...
Which is straight up invalid HTML, that sanitizing parsers like caja will reject. I had a fun of telling a client, that I will not purposefully break parsing algorithm of a HTML sanitizing parser just so that their customers can read mails from their bank.
(Experiences from writing a web mail client to be used in a real world.)
Basically almost everyone puts anything there so that they get some visually pleasing result, the markup semantics be damned.
One would think that lack of features of various mail clients would lead to using the lowest common denominator of some basic tags like b, i, a, hr, and maybe img.
Not so in reality.
One bank I've seen e-mails from even abuses invalid parsing of HTML comments, to produce whatever insane result someone somewhere dreamed up, like this:
Which is straight up invalid HTML, that sanitizing parsers like caja will reject. I had a fun of telling a client, that I will not purposefully break parsing algorithm of a HTML sanitizing parser just so that their customers can read mails from their bank.(Experiences from writing a web mail client to be used in a real world.)