Dear businesses that post us marketing material through email,
I read my mail in plaintext, like many other people do. Not in the least because I can set my favorite font type, size and color and have absolutely nothing interfere with that preference.
It's frustrating when you send me an email that tells me "my client cannot read this email". Surely, the clients for Kolab Groupware (which I use, and develop, and support, and architect) can read your email, but you neglected to provide a legible equivalent of what you wanted to tell me.
I'm sure you're very fond of your undoubtedly stunningly beautiful markup, after all you employ people to work on that for you, but ignoring the fact people might actually just want to read some content is bluntly ignorant, and offensive.
I wonder whether you care enough. All I want is to just read about what you wanted to tell me without oversized headers, too small fonts for paragraphs, social media logos, login links, and screaming background colors being thrown in my face.
Not only do you not care enough to send me a legible version of your message, you don't even care enough to correct the message that tells me what is displayed on my screen is not what you wanted to say. The facts of the matter are relatively straight-forward;
So, please allow me to help you resolve this problem; An email that you sent with HTML can contain two(!) parts, and you can mark those parts as an alternative equivalent of the other part.
For the part that is the HTML equivalent, feel free to knock yourselves out.
For the plain text equivalent, please provide some useful content. I recommend you consider marking a header and lists such as you would do marking up the source of a wiki page, but whatever you do don't invent something you think is nice yourselves. Perhaps consider wrapping the lines at some 72 characters. A link you may need to refer to in the text can be referred to like this
We have a new product.
Those links do not (need to) include the social media links, and "my account", and opt-in, and opt-out, and subscription status, and contact, and mobile site, and the web version of the marketing collateral (really, some do include all of the above).