What Is Multipart/Alternative?
Multipart/alternative emails contain both plain text and HTML. What a user sees depends on their set preferences or what’s allowed by their email client. If an email client can’t render HTML messages, it will display the plain text version. HTML-enabled email programs will usually show the rich HTML version unless users have set a preference for plain-text email only. Sending multipart alternative messages is a great solution to reach all your subscribers without having to maintain two separate lists.
How It Works
To deliver your marketing messages as multipart/alternative emails, make sure your email marketing software or service provider supports this format. Some service providers create a plain text version of your HTML messages automatically, but it’s important to verify the quality of that message. Usually, you’ll compose both a rich HTML version of your message and a plain text equivalent, and then send them together as one multipart alternative message.
How Does Multipart Alternative Work?
Multipart alternative emails make use of the MIME email standard. The individual parts are sent similarly to attached files, so email programs recognize them as alternative versions. Rather than showing all versions of the email, it displays only the preferred version. The alternative versions in a multipart/alternative email are separated by a boundary marker, which is identical for all versions. Each email version also has a MIME content type assigned. This is where the versions differ. With multipart alternative marketing emails, the content types will typically be “text/plain” and “text/HTML.” The types follow each other, and email programs will usually display the last version they’re capable of showing. This means “text/plain” followed by “text/HTML” in multipart alternative emails unless users have set a certain preference.
Multipart/Alternative Example
The source of an email using multipart alternative formatting could look like this:
