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smtp(3tcl) smtp client smtp(3tcl) 





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:







  

  
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.

  

  

  
A list of SMTP ports. The default is 25.
    
See option -servers above regardig the behaviour for
        then multiple servers and ports are specified.

  

  

  
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.

  

  
Indicates that the SMTP server should be asked to queue the message for
      later processing. A boolean value.

  

  
Indicates that the SMTP server must find at least one recipient acceptable
      for the message to be sent. A boolean value.

  

  
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). If the string
      contains more than one address they will be separated by commas.

  
  
A list containing two elements, an smtp header and its associated value
      (the -header option may occur zero or more times).

  

  
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.

  

  
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.

  

  
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.

  

  

  

  
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








  

    1.5.1
    tcllib