Content-Type: multipart/alternative in Wordpress with wp_mail()
content-type, multipart-alternative, wordpress
Solution
It's right there in the `wp_mail()` documentation (under Usage):
The default content type is 'text/plain' which does not allow using HTML. You can set the content type of the email either by using the 'wp_mail_content_type' filter (see example below), or by including a header like "Content-type: text/html". Be careful to reset 'wp_mail_content_type' back to 'text/plain' after you send your message, though, because failing to do so could lead to unexpected problems with e-mails from WP or plugins/themes.
(emphasis mine)
The 2nd example on the page shows you how to do it (the example uses `text/html` but you should be able to use your `multipart/alternative` instead.
Problem
Is it is possible to send emails with the wp_mail() function having its Content-Type: multipart/alternative ? I need to send emails that can be shown as HTML or Plain Text depending on what medium interprets the email. Any suggestions are welcome!