How HTML Email Works

How HTML Email Works
Before you can start designing, coding, and sending HTML emails, you should know how
it works and what tools you’ll need. Here’s some background information every email
designer and marketer should know…
The Multipart/Alternative MIME Format
The most important thing you need to know about HTML email is that you can’t just
attach an HTML file and a bunch of images to a message and hit “send.” Most of the
time, your recipients’ email applications will break all the paths to your image files
(because they’ll move your images into temporary folders on your hard drive). And you
can’t just paste all your code into your email application, either. Most email apps send
messages in “plain-text” format by default, so the HTML won’t render. Your recipients
would just see all that raw source code, instead of the pretty email it’s supposed to
render.
You need to send HTML email from your server in “Multipart-Alternative MIME format.”
Basically, that means your mail transfer agent bundles your HTML code, PLUS a plain-text
version of the message, together into one email. That way, if a recipient can’t view
your beautiful HTML email, the good-old-fashioned plain-text version of your message is
auto-magically displayed. It’s kind of a nerdy gobbledy-geek thing, which is why a lot of
people mess things up when they try to send HTML email themselves. You either need
to program a script to send email in multipart/alternative MIME format, or just use an
outside vendor (ahem, like MailChimp) to deliver things for you.