Is it sensible to send HTML-only email these days?

Question

I want my web app to send certain mails as HTML in order to include product images.

I could of course provide a text/plain alternative as well, but is it worth the effort in this day and age? Are there common mail clients that don't support text/html, do many people turn it off for some good reason (I suppose spam, bandwidth), are there other reasons such as decreasing the risk of being classified as spam?

I can theorize, but would be interested to hear if someone has statistics, experience or other insight to support or speak against going text/html only.

Answer 1

You are best to send both because:

• It helps reduce your spam score, even more so if your text version has the same text and links as your HTML version. This is especially true on Outlook, where no text version almost guarantees it will go the Junk folder.
• A lot of people do request a text version on the client-side. Some old Blackberries default to this setting, and Windows Mobile <= v5.

Answer 2

Provide both. HTML in email has a slew of security problems, so those that are security-minded tend to disable HTML email in favor of plain text. Also, reply quoting conventions are fairly well-establised for text/plain data and not for HTML, making meaningful discussions in pure-HTML mail threads ugly.

Since you do have control over the content of the message, please make the plain text version readable. Some MUAs tend to auto-create the text/plain part, and do a horrible job in doing so. So if your messages are intended for customers, make sure the text/plain part is formatted nicely so you do not alienate them.