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The structure and rendering of multipart emails
Nov 3, 2021

The structure and rendering of multipart emails

How do multipart emails work?

When marked as multipart/alternative, an email message can contain multiple versions of the same content which allows the email client to render the message in the most appropriate format for the user's device. In most cases, two versions are included: the plaintext version (text/plain) and HTML version (text/html). Other content types such as AMP (text/x-amp-html) are often used in conjunction with the plaintext and HTML versions.

See also
SMTP Testing Tool
Test SMTP server communication using the email testing tool.
Receiving email with Node.js
How to receive email in Node.js?
cid URLs for email developers
What are cid URLs and how are they interpreted by email clients?
MAIL FROM and RCPT TO vs. the To and From headers
The difference between the email envelope and message headers when it comes to senders and recipients.