Now regarding your point about the recipient (firstname, lastname): coming from a different culture myself (fr-CA), I truly understand your concern. In French, addressing someone on a firstname basis is indeed annoying (well for me at least and I am not that old:-). I would be really interested in hearing your alternatives. How to you circumvent this?
HTML email is indeed tricky and I realize I should have mention it. However, there are interesting solutions out there to test both the rendering on various client and its spam sensibility. I have personally used service from Campaign Monitor which provided useful information. Check the following:
http://www.campaignmonitor.com/design-guidelines/
http://www.campaignmonitor.com/testing/
http://litmus.com/email-previews
http://www.email-standards.org/
I think your concern about up-sell technique could be legit for some B2C markets. However, my experience with B2B (and I have metrics to back my statement) shows that the negative impact of such up-sell is minimal in most situation while being straight positive in some others. I DID get up-sell conversions using such technique. But then again, I think this kind up-sell should remain as light as possible. Not really the in-your-face-billboard type.
This is all about knowing your target audience and adapt accordingly.
I am far from an expert though. I'm a hacker not a marketer :-) I just happen to be interested in such communication, unavoidable being an entrepreneur.
Personalising by first/last name is a well-known screw-up if you're working with international markets. Numerous cultures put their surname first, assuming they even recognise the distinction at all. Also, being "chummy" by addressing mails to someone on a first-name basis will annoy a significant number of people, particularly those from older generations or, again, from various cultures other than English-speaking Western ones.
HTML e-mail is commonly accepted these days, but you need to know what you're doing. If you send something that looks cute in your mail client, that is no guarantee at all that it will render even sensibly, never mind identically, in other popular mail clients. Also, various things related to HTML e-mails are common markers for spam, and if it's the first time you're writing to a customer you're already the wrong side of average on a lot of popular mail systems these days.
Finally, the upsell-in-conclusion idea sounds dangerous to me. If I've trusted a company with my e-mail address and the first thing I get back is something trying to sell me more stuff rather than support whatever it was I signed up for, then my opinion of that company will instantly drop.
