The README fileM. Rose
 Dover Beach Consulting, Inc.
 February 2000



Tcl MIME generates and parses MIME body parts.


Table of Contents



    package provide mime 1.2
    package provide smtp 1.2

Tcl MIME is an implementation of a Tcl package that generates and parses MIME[1] body parts.

Each MIME part consists of a header (zero or more key/value pairs), an empty line, and a structured body. A MIME part is either a "leaf" or has (zero or more) subordinates.

MIME defines four keys that may appear in the headers:

describes the data contained in the body ("the content");
describes how the content is encoded for transmission in an ASCII stream;
a textual description of the content; and,
a globally-unique identifier for the content.

Consult [2] for a list of standard content types. Further, consult [3] for a list of several other header keys (e.g., "To", "cc", etc.)

A simple example might be:

    Date: Sun, 04 July 1999 10:38:25 -0600
    From: Marshall Rose <>
    To: Andreas Kupries <>
    cc: (Darren New)
    MIME-Version: 1.0
    Content-Type: text/plain; charset="us-ascii"
    Content-Description: a simple example
    Content-ID: <>
    Here is the body. In this case, simply plain text.

In addition to an implementation of the mime package, Tcl MIME includes an implementation of the smtp package.

1.1 Requirements

This package requires:

1.2 Copyrights

(c) 1999-2000 Marshall T. Rose

Hold harmless the author, and any lawful use is allowed.



mime::initialize returns a token. Parameters:

    ?-canonical type/subtype
        ?-param    {key value}?...
        ?-encoding value?
        ?-header   {key value}?... ?
    (-file name | -string value | -parts {token1 ... tokenN})

mime::finalize returns an empty string. Parameters:

    token ?-subordinates "all" | "dynamic" | "none"?

mime::getproperty returns a string or a list of strings. Parameters:

    token ?property | -names?

mime::getheader returns a list of strings. Parameters:

    token ?key | -names?

mime::setheader returns a list of strings. Parameters:

    token key value ?-mode "write" | "append" | "delete"?

mime::getbody returns a string. Parameters:

    ?-command callback ?-blocksize octets? ?

mime::copymessage returns an empty string. Parameters:

    token channel

smtp::sendmessage returns a list. Parameters:

    token ?-servers list?
          ?-queue boolean?     ?-atleastone boolean?
          ?-originator string? ?-recipients string?
          ?-header {key value}?...

mime::parseaddress returns a list of serialized arrays. Parameters:


mime::parsedatetime returns a string. Parameters:

    [string | -now] property



3.1 mime::initialize

mime::initialize creates a MIME part:

3.2 mime::finalize

mime::finalize destroys a MIME part.

If the -subordinates option is present, it specifies which subordinates should be also be destroyed. The default value is "dynamic".

3.3 mime::getproperty

mime::getproperty returns the properties of a MIME part.

The properties are:

    property    value
    ========    =====
    content     the type/subtype describing the content
    encoding    the "Content-Transfer-Encoding"
    params      a list of "Content-Type" parameters
    parts       a list of tokens for the part's subordinates
    size        the approximate size of the content (unencoded)

The "parts" property is present only if the MIME part has subordinates.

If mime::getproperty is invoked with the name of a specific property, then the corresponding value is returned; instead, if -names is specified, a list of all properties is returned; otherwise, a serialized array of properties and values is returned.

3.4 mime::getheader

mime::getheader returns the header of a MIME part.

A header consists of zero or more key/value pairs. Each value is a list containing one or more strings.

If mime::getheader is invoked with the name of a specific key, then a list containing the corresponding value(s) is returned; instead, if -names is specified, a list of all keys is returned; otherwise, a serialized array of keys and values is returned. Note that when a key is specified (e.g., "Subject"), the list returned usually contains exactly one string; however, some keys (e.g., "Received") often occur more than once in the header, accordingly the list returned usually contains more than one string.

3.5 mime::setheader

mime::setheader writes, appends to, or deletes the value associated with a key in the header.

The value for -mode is one of:

the key/value is either created or overwritten (the default);
a new value is appended for the key (creating it as necessary); or,
all values associated with the key are removed (the "value" parameter is ignored).

Regardless, mime::setheader returns the previous value associated with the key.

3.6 mime::getbody

mime::getbody returns the body of a leaf MIME part in canonical form.

If the -command option is present, then it is repeatedly invoked with a fragment of the body as this:

    uplevel #0 $callback [list "data" $fragment]

(The -blocksize option, if present, specifies the maximum size of each fragment passed to the callback.)

When the end of the body is reached, the callback is invoked as:

    uplevel #0 $callback "end"

Alternatively, if an error occurs, the callback is invoked as:

    uplevel #0 $callback [list "error" reason]

Regardless, the return value of the final invocation of the callback is propagated upwards by mime::getbody.

If the -command option is absent, then the return value of mime::getbody is a string containing the MIME part's entire body.

3.7 mime::copymessage

mime::copymessage copies the MIME part to the specified channel.

mime::copymessage operates synchronously, and uses fileevent to allow asynchronous operations to proceed independently.

3.8 smtp::sendmessage

smtp::sendmessage sends a MIME part to an SMTP server. (Note that this procedure is in the "smtp" package, not the "mime" package.)

The options are:

a list of SMTP servers (the default is "localhost");
indicates that the SMTP server should be asked to queue the message for later processing;
indicates that the SMTP server must find at least one recipient acceptable for the message to be sent;
a string containing an 822-style address specification (if present the header isn't examined for an originator address);
a string containing one or more 822-style address specifications (if present the header isn't examined for recipient addresses); and,
a keyword/value pairing (may occur zero or more times).

If the -originator option is not present, the originator address is taken from "From" (or "Resent-From"); similarly, if the -recipients option is not present, recipient addresses are taken from "To", "cc", and "Bcc" (or "Resent-To", and so on). Note that the header key/values supplied by the "-header" option (not those present in the MIME part) are consulted. Regardless, header key/values are added to the outgoing message as necessary to ensure that a valid 822-style message is sent.

smtp::sendmessage returns a list indicating which recipients were unacceptable to the SMTP server. Each element of the list is another list, containing the address, an SMTP error code, and a textual diagnostic. Depending on the -atleastone option and the intended recipients,, a non-empty list may still indicate that the message was accepted by the server.

3.9 mime::parseaddress

mime::parseaddr takes a string containing one or more 822-style address specifications and returns a list of serialized arrays, one element for each address specified in the argument.

Each serialized array contains these properties:

    property    value
    ========    =====
    address     local@domain
    comment     822-style comment
    domain      the domain part (rhs)
    error       non-empty on a parse error 
    group       this address begins a group
    friendly    user-friendly rendering
    local       the local part (lhs)
    memberP     this address belongs to a group
    phrase      the phrase part
    proper      822-style address specification
    route       822-style route specification (obsolete)

Note that one or more of these properties may be empty.

3.10 mime::parsedatetime

mime::parsedatetime takes a string containing an 822-style date-time specification and returns the specified property.

The list of properties and their ranges are:

    property     range
    ========     =====
    hour         0 .. 23
    lmonth       January, February, ..., December
    lweekday     Sunday, Monday, ... Saturday
    mday         1 .. 31
    min          0 .. 59
    mon          1 .. 12
    month        Jan, Feb, ..., Dec
    proper       822-style date-time specification
    rclock       elapsed seconds between then and now
    sec          0 .. 59
    wday         0 .. 6 (Sun .. Mon)
    weekday      Sun, Mon, ..., Sat
    yday         1 .. 366
    year         1900 ...
    zone         -720 .. 720 (minutes east of GMT)



package require mime 1.0
package require smtp 1.0

# create an image

set imageT [mime::initialize -canonical image/gif \
                             -file logo.gif]

# parse a message

set messageT [mime::initialize -file example.msg]

# recursively traverse a message looking for primary recipients

proc traverse {token} {
    set result ""

# depth-first search
    if {![catch { mime::getproperty $token parts } parts]} {
        foreach part $parts {
            set result [concat $result [traverse $part]]

# one value for each line occuring in the header
    foreach value [mime::getheader $token To] {
        foreach addr [mime::parseaddress $value] {
            catch { unset aprops }
            array set aprops $addr
            lappend result $aprops(address)

    return $result

# create a multipart containing both, and a timestamp

set multiT [mime::initialize -canonical multipart/mixed
                             -parts [list $imageT $messageT]]

# send it to some friends

smtp::sendmessage $multiT \
      -header [list From "Marshall Rose <>"] \
      -header [list To "Andreas Kupries <>"] \
      -header [list cc " (Darren New)"] \
      -header [list Subject "test message..."]

# clean everything up

mime::finalize $multiT -subordinates all



[1] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC 2045, November 1996.
[2] Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types", RFC 2046, November 1995.
[3] Crocker, D., "Standard for the format of ARPA Internet Text Messages", RFC 822, STD 11, August 1982.


Author's Address

  Marshall T. Rose
  Dover Beach Consulting, Inc.
  POB 255268
  Sacramento, CA 95865-5268
Phone:  +1 916 483 8878
Fax:  +1 916 483 8848


Appendix A. TODO List

  • well-defined errorCode values
  • catch nested errors when processing a multipart


Appendix B. Acknowledgements

This package is influenced by the safe-tcl package (Borenstein and Rose, circa 1993), and also by Darren New's unpublished package of 1999.

This package makes use of Andreas Kupries's excellent Trf package.