2.2 MML Definition

The MML language is very simple. It looks a bit like an SGML application, but it's not.

The main concept of MML is the part. Each part can be of a different type or use a different charset. The way to delineate a part is with a ‘<#part ...>’ tag. Multipart parts can be introduced with the ‘<#multipart ...>’ tag. Parts are ended by the ‘<#/part>’ or ‘<#/multipart>’ tags. Parts started with the ‘<#part ...>’ tags are also closed by the next open tag.

There's also the ‘<#external ...>’ tag. These introduce ‘external/message-body’ parts.

Each tag can contain zero or more parameters on the form ‘parameter=value’. The values may be enclosed in quotation marks, but that's not necessary unless the value contains white space. So ‘filename=/home/user/#hello$^yes’ is perfectly valid.

The following parameters have meaning in MML; parameters that have no meaning are ignored. The MML parameter names are the same as the MIME parameter names; the things in the parentheses say which header it will be used in.

‘type’

The MIME type of the part (Content-Type).

‘filename’

Use the contents of the file in the body of the part (Content-Disposition).

‘charset’

The contents of the body of the part are to be encoded in the character set specified (Content-Type). See Charset Translation.

‘name’

Might be used to suggest a file name if the part is to be saved to a file (Content-Type).

‘disposition’

Valid values are ‘inline’ and ‘attachment’ (Content-Disposition).

‘encoding’

Valid values are ‘7bit’, ‘8bit’, ‘quoted-printable’ and ‘base64’ (Content-Transfer-Encoding). See Charset Translation.

‘description’

A description of the part (Content-Description).

‘creation-date’

RFC822 date when the part was created (Content-Disposition).

‘modification-date’

RFC822 date when the part was modified (Content-Disposition).

‘read-date’

RFC822 date when the part was read (Content-Disposition).

‘recipients’

Who to encrypt/sign the part to. This field is used to override any auto-detection based on the To/CC headers.

‘sender’

Identity used to sign the part. This field is used to override the default key used.

‘size’

The size (in octets) of the part (Content-Disposition).

‘sign’

What technology to sign this MML part with (smime, pgp or pgpmime)

‘encrypt’

What technology to encrypt this MML part with (smime, pgp or pgpmime)

Parameters for ‘text/plain’:

‘format’

Formatting parameter for the text, valid values include ‘fixed’ (the default) and ‘flowed’. Normally you do not specify this manually, since it requires the textual body to be formatted in a special way described in RFC 2646. See Flowed text.

Parameters for ‘application/octet-stream’:

‘type’

Type of the part; informal—meant for human readers (Content-Type).

Parameters for ‘message/external-body’:

‘access-type’

A word indicating the supported access mechanism by which the file may be obtained. Values include ‘ftp’, ‘anon-ftp’, ‘tftp’, ‘localfile’, and ‘mailserver’. (Content-Type.)

‘expiration’

The RFC822 date after which the file may no longer be fetched. (Content-Type.)

‘size’

The size (in octets) of the file. (Content-Type.)

‘permission’

Valid values are ‘read’ and ‘read-write’ (Content-Type).

Parameters for ‘sign=smime’:

‘keyfile’

File containing key and certificate for signer.

Parameters for ‘encrypt=smime’:

‘certfile’

File containing certificate for recipient.