Provided by: tcllib_1.21+dfsg-1_all 
NAME
smtp - Client-side tcl implementation of the smtp protocol
SYNOPSIS
package require Tcl
package require mime ?1.5.4?
package require smtp ?1.5.1?
::smtp::sendmessage token option...
________________________________________________________________________________________________________________
DESCRIPTION
The smtp library package provides the client side of the Simple Mail Transfer Protocol (SMTP) (1) (2).
::smtp::sendmessage token option...
This command sends the MIME part (see package mime) represented by token to an SMTP server.
options is a list of options and their associated values. The recognized options are:
-servers
A list of SMTP servers. The default is localhost.
If multiple servers are specified they are tried in sequence. Note that the -ports are
iterated over in tandem with the servers. If there are not enough ports for the number of
servers the default port (see below) is used. If there are more ports than servers the
superfluous ports are ignored.
-ports A list of SMTP ports. The default is 25.
See option -servers above regardig the behaviour for then multiple servers and ports are
specified.
-client
The name to use as our hostname when connecting to the server. By default this is either
localhost if one of the servers is localhost, or is set to the string returned by info
hostname.
-queue Indicates that the SMTP server should be asked to queue the message for later processing. A
boolean value.
-atleastone
Indicates that the SMTP server must find at least one recipient acceptable for the message
to be sent. A boolean value.
-originator
A string containing an 822-style address specification. If present the header isn't
examined for an originator address.
-recipients
A string containing one or more 822-style address specifications. If present the header
isn't examined for recipient addresses). If the string contains more than one address they
will be separated by commas.
-header
A list containing two elements, an smtp header and its associated value (the -header option
may occur zero or more times).
-usetls
This package supports the RFC 3207 TLS extension (3) by default provided the tls package is
available. You can turn this off with this boolean option.
-tlsimport
This boolean flag is false by default. When this flag is set the package will import TLS
on a sucessfully opened channel. This is needed for connections using native TLS
negotiation instead of STARTTLS. The tls package is automatically required when needed.
-tlspolicy
This option lets you specify a command to be called if an error occurs during TLS setup.
The command is called with the SMTP code and diagnostic message appended. The command
should return 'secure' or 'insecure' where insecure will cause the package to continue on
the unencrypted channel. Returning 'secure' will cause the socket to be closed and the
next server in the -servers list to be tried.
-username
-password
If your SMTP server requires authentication (RFC 2554 (4)) before accepting mail you can
use -username and -password to provide your authentication details to the server. Currently
this package supports DIGEST-MD5, CRAM-MD5, LOGIN and PLAIN authentication methods. The
most secure method will be tried first and each method tried in turn until we are either
authorized or we run out of methods. Note that if the server permits a TLS connection, then
the authorization will occur after we begin using the secure channel.
Please also read the section on Authentication, it details the necessary prequisites, i.e.
packages needed to support these options and authentication.
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.
The command 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.
AUTHENTICATION
Beware. SMTP authentication uses SASL. I.e. if the user has to authenticate a connection, i.e. use the
options -user and -password (see above) it is necessary to have the sasl package available so that smtp
can load it.
This is a soft dependency because not everybody requires authentication, and sasl depends on a lot of the
cryptographic (secure) hashes, i.e. all of md5, otp, md4, sha1, and ripemd160.
EXAMPLE
proc send_simple_message {recipient email_server subject body} {
package require smtp
package require mime
set token [mime::initialize -canonical text/plain \
-string $body]
mime::setheader $token Subject $subject
smtp::sendmessage $token \
-recipients $recipient -servers $email_server
mime::finalize $token
}
send_simple_message someone@somewhere.com localhost \
"This is the subject." "This is the message."
TLS SECURITY CONSIDERATIONS
This package uses the TLS package to handle the security for https urls and other socket connections.
Policy decisions like the set of protocols to support and what ciphers to use are not the responsibility
of TLS, nor of this package itself however. Such decisions are the responsibility of whichever
application is using the package, and are likely influenced by the set of servers the application will
talk to as well.
For example, in light of the recent POODLE attack
[http://googleonlinesecurity.blogspot.co.uk/2014/10/this-poodle-bites-exploiting-ssl-30.html] discovered
by Google many servers will disable support for the SSLv3 protocol. To handle this change the
applications using TLS must be patched, and not this package, nor TLS itself. Such a patch may be as
simple as generally activating tls1 support, as shown in the example below.
package require tls
tls::init -tls1 1 ;# forcibly activate support for the TLS1 protocol
... your own application code ...
REFERENCES
[1] Jonathan B. Postel, "SIMPLE MAIL TRANSFER PROTOCOL", RFC 821, August 1982. (http://www.rfc-
editor.org/rfc/rfc821.txt)
[2] J. Klensin, "Simple Mail Transfer Protocol", RFC 2821, April 2001. (http://www.rfc-
editor.org/rfc/rfc2821.txt)
[3] P. Hoffman, "SMTP Service Extension for Secure SMTP over Transport Layer Security", RFC 3207,
February 2002. (http://www.rfc-editor.org/rfc/rfc3207.txt)
[4] J. Myers, "SMTP Service Extension for Authentication", RFC 2554, March 1999. (http://www.rfc-
editor.org/rfc/rfc2554.txt)
BUGS, IDEAS, FEEDBACK
This document, and the package it describes, will undoubtedly contain bugs and other problems. Please
report such in the category smtp of the Tcllib Trackers [http://core.tcl.tk/tcllib/reportlist]. Please
also report any ideas for enhancements you may have for either package and/or documentation.
When proposing code changes, please provide unified diffs, i.e the output of diff -u.
Note further that attachments are strongly preferred over inlined patches. Attachments can be made by
going to the Edit form of the ticket immediately after its creation, and then using the left-most button
in the secondary navigation bar.
SEE ALSO
ftp, http, mime, pop3
KEYWORDS
email, internet, mail, mime, net, rfc 2554, rfc 2821, rfc 3207, rfc 821, rfc 822, smtp, tls
CATEGORY
Networking
COPYRIGHT
Copyright (c) 1999-2000 Marshall T. Rose and others
tcllib 1.5.1 smtp(3tcl)