I'm curious to find out how others have handled sending out html-based email
(as in direct email marketing campaigns) while accounting for those who have
clients that don't support HTML. Is there a way to recognize whether the
client can handle email as the message is being loaded and then handle it
somehow? Are the stats on the number of users with HTML - enabled email
clients so high that it isn't a concern? Is there a way to hide the HTML
from non-html clients?

Thanks in advance for any information!