[tomwalsham]

I completely agree. These days there's very little wrong with sending HTML-based transactional email provided you've covered your bases on all other potential flags and send as multipart with a plaintext component. At PostageApp many clients have amazing inbox delivery with HTML transactional, and the benefits - improved tracking, better funnel direction etc. - outweigh the minor delivery drawbacks in many cases.

Frankly, many who send 'plaintext' transactional in fact end up sending as HTML these days in order to facilitate open tracking from embedded images, so aren't gaining much beyond avoiding the minor issues like 'HTML_IMAGE_RATIO' etc.

edit Apparently the MailRox invite email _is_ an HTML email for the exact reasons outlined above. I can see no reason why you wouldn't want to add some visual sparkle to this based on that fact. Incidentally, you're sending without a plaintext component which can cause delivery problems at some ISPs.