Are the consequences similar, no matter where I open the potentially harmful mail from, be it webmail or Outlook? Hmm...
Yes, I would expect so - probably even easier in webmail since you're already looking at it in a browser that's designed to load images from all over the internet.
Unless, of course, the webmail service gives you some measure of control over what you choose to display while you're online.
1. Yes it's old but still valid - there is no reason to send HTML in an email. Any sent to me usually end up deleted rather than read and I blame it on a message filter if someone asks I tried that for a while, and all it did was piss people off. Seriously.
The obvious answer to those people is, "Well, I don't know how valuable your personal data is but I actually take steps to protect mine."
Alternatively, you could scramble the <html> tags and forward it back to them asking where in the load of rubbish is the pertinent information.
For a while I actually toyed with the idea of creating a filter that auto-responded with that website before deleting the offending message.
Now-a-days people tend to know me better and don't send me things I have no intention of looking at, (like bl**dy PowerPoint attachments for stupid jokes), because they know it'll just get deleted.
it's old but still valid - there is no reason to send HTML in an email.
is anyone aware of a reason why HTML mail persists?
That's easy, have a look at any PC running Windows - OE, (and probably Outlook), and Thunderbird, (IIRC, it's been awhile since I last installed let alone configured it), both default to HTML email and replying to email in the format it was sent.
I don't know about any other email clients but since you're talking about probably the most used one, (OE), it comes back to being "people don't know any better."
They see the pretty emails they can send but they don't see all the junk that's sent to do it, neither are they aware of the risk involved in receiving the damn things.