Message Composition with MML (MIME Meta Language)

Himalaya uses MML for composing emails. MML is a simple XML-based syntax that compiles to MIME messages.

Basic Message Structure

An email message is a list of headers followed by a body, separated by a blank line:

From: [email protected]
To: [email protected]
Subject: Hello World

This is the message body.

Headers

Common headers:

From: Sender address
To: Primary recipient(s)
Cc: Carbon copy recipients
Bcc: Blind carbon copy recipients
Subject: Message subject
Reply-To: Address for replies (if different from From)
In-Reply-To: Message ID being replied to

Address Formats

To: [email protected]
To: John Doe <[email protected]>
To: "John Doe" <[email protected]>
To: [email protected], [email protected], "Jane" <[email protected]>

Plain Text Body

Simple plain text email:

From: alice@localhost
To: bob@localhost
Subject: Plain Text Example

Hello, this is a plain text email.
No special formatting needed.

Best,
Alice

MML for Rich Emails

Multipart Messages

Alternative text/html parts:

From: alice@localhost
To: bob@localhost
Subject: Multipart Example

<#multipart type=alternative>
This is the plain text version.
<#part type=text/html>
<html><body><h1>This is the HTML version</h1></body></html>
<#/multipart>

Attachments

Attach a file:

From: alice@localhost
To: bob@localhost
Subject: With Attachment

Here is the document you requested.

<#part filename=/path/to/document.pdf><#/part>

Attachment with custom name:

<#part filename=/path/to/file.pdf name=report.pdf><#/part>

Multiple attachments:

<#part filename=/path/to/doc1.pdf><#/part>
<#part filename=/path/to/doc2.pdf><#/part>

Inline Images

Embed an image inline:

From: alice@localhost
To: bob@localhost
Subject: Inline Image

<#multipart type=related>
<#part type=text/html>
<html><body>
<p>Check out this image:</p>

</body></html>
<#part disposition=inline id=image1 filename=/path/to/image.png><#/part>
<#/multipart>

Mixed Content (Text + Attachments)

From: alice@localhost
To: bob@localhost
Subject: Mixed Content

<#multipart type=mixed>
<#part type=text/plain>
Please find the attached files.

Best,
Alice
<#part filename=/path/to/file1.pdf><#/part>
<#part filename=/path/to/file2.zip><#/part>
<#/multipart>

MML Tag Reference

`<#multipart>`

Groups multiple parts together.

type=alternative: Different representations of same content
type=mixed: Independent parts (text + attachments)
type=related: Parts that reference each other (HTML + images)

`<#part>`

Defines a message part.

type=<mime-type>: Content type (e.g., text/html, application/pdf)
filename=<path>: File to attach
name=<name>: Display name for attachment
disposition=inline: Display inline instead of as attachment
id=<cid>: Content ID for referencing in HTML

Composing from CLI

Interactive compose

Opens your $EDITOR:

bash

himalaya message write

Reply (opens editor with quoted message)

bash

himalaya message reply 42
himalaya message reply 42 --all  # reply-all

Forward

bash

himalaya message forward 42

Send from stdin

bash

cat message.txt | himalaya template send

Prefill headers from CLI

bash

himalaya message write \
  -H "To:[email protected]" \
  -H "Subject:Quick Message" \
  "Message body here"

Tips

The editor opens with a template; fill in headers and body.
Save and exit the editor to send; exit without saving to cancel.
MML parts are compiled to proper MIME when sending.
Use himalaya message export --full to inspect the raw MIME structure of received emails.