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muttdown is a sendmail-replacement designed for use with the mutt email client which will transparently compile annotated text/plain mail into text/html using the Markdown standard. It will recursively walk the MIME tree and compile any text/plain or text/markdown part which begins with the sigil "!m" into Markdown, which it will insert alongside the original in a multipart/alternative container.

It's also smart enough not to break multipart/signed.

For example, the following tree before parsing:

- multipart/mixed
 -- multipart/signed
 ---- text/markdown
 ---- application/pgp-signature
 -- image/png

Will get compiled into

- multipart/mixed
 -- multipart/alternative
 ---- text/html
 ---- multipart/signed
 ------ text/markdown
 ------ application/pgp-signature
 -- image/png


Muttdown's configuration file is written using YAML. Example:

smtp_port: 587
smtp_ssl: false
smtp_password: foo
css_file: ~/.muttdown.css
assume_markdown: false

If you prefer not to put your password in plaintext in a configuration file, you can instead specify the smtp_password_command parameter to invoke a shell command to lookup your password. The command should output your password, followed by a newline, and no other text. On OS X, the following invocation will extract a generic "Password" entry with the application set to "mutt" and the title set to "":

smtp_password_command: security find-generic-password -w -s mutt -a

NOTE: If smtp_ssl is set to False, muttdown will do a non-SSL session and then invoke STARTTLS. If smtp_ssl is set to True, muttdown will do an SSL session from the get-go. There is no option to send mail in plaintext.

The css_file should be regular CSS styling blocks; we use pynliner to inline all CSS rules for maximum client compatibility.

Muttdown can also send its mail using the native sendmail if you have that set up (instead of doing SMTP itself). To do so, just leave the smtp options in the config file blank, set the sendmail option to the fully-qualified path to your sendmail binary, and run muttdown with the -s flag

If assume_markdown is true, then all input is assumed to be Markdown by default and the !m sigil does nothing.


Install muttdown with pip install muttdown or by downloading this package and running python install. You will need the PyYAML and Python-Markdown libraries, as specified in requirements.txt. This should work with Python 3.6+.


Invoke as

muttdown -c /path/to/config -f "from_address" -- "to_address" [more to addresses...]

Send a RFC822 formatted mail on stdin.

If the config path is not passed, it will assume ~/.muttdown.yaml.