What is MIME (Multipurpose Internet Mail Extensions)?

MIME (Multipurpose Internet Mail Extensions) is the standard that allows email to contain more than plain ASCII text. Without MIME, email couldn't support HTML formatting, images, attachments, or characters from non-English languages.

MIME was introduced in RFC 1341 in 1992 and has evolved through subsequent RFCs. It solved fundamental limitations of the original email specification, which only supported 7-bit ASCII text.

What MIME enables:

Content types: Declaring what kind of content a message part contains (text/plain, text/html, image/png, application/pdf)

Multipart messages: Combining multiple content types in one email (HTML and plain text versions, or message body plus attachments)

Character encoding: Supporting international characters through UTF-8 and other encodings

Binary content: Encoding attachments as Base64 for safe transmission through text-only systems

Every modern email uses MIME. The Content-Type header declares the format; Content-Transfer-Encoding specifies how binary data is encoded; boundary markers separate multipart sections.

MIME is the container standard that lets you ship any cargo, not just text messages. It standardized how to package different content types for the email transport system.