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Section: Perl Programmers Reference Guide (3)
Updated: 2001-09-21
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Net::SMTP - Simple Mail Transfer Protocol Client  


    use Net::SMTP;

    # Constructors
    $smtp = Net::SMTP->new('mailhost');
    $smtp = Net::SMTP->new('mailhost', Timeout => 60);



This module implements a client interface to the SMTP and ESMTP protocol, enabling a perl5 application to talk to SMTP servers. This documentation assumes that you are familiar with the concepts of the SMTP protocol described in RFC821.

A new Net::SMTP object must be created with the new method. Once this has been done, all SMTP commands are accessed through this object.

The Net::SMTP class is a subclass of Net::Cmd and IO::Socket::INET.  


This example prints the mail domain name of the SMTP server known as mailhost:

    #!/usr/local/bin/perl -w

    use Net::SMTP;

    $smtp = Net::SMTP->new('mailhost');
    print $smtp->domain,"\n";

This example sends a small message to the postmaster at the SMTP server known as mailhost:

    #!/usr/local/bin/perl -w

    use Net::SMTP;

    $smtp = Net::SMTP->new('mailhost');


    $smtp->datasend("To: postmaster\n");
    $smtp->datasend("A simple test message\n");




new ( [ HOST ] [, OPTIONS ] )
This is the constructor for a new Net::SMTP object. "HOST" is the name of the remote host to which an SMTP connection is required.

"HOST" is optional. If "HOST" is not given then it may instead be passed as the "Host" option described below. If neither is given then the "SMTP_Hosts" specified in "Net::Config" will be used.

"OPTIONS" are passed in a hash like fashion, using key and value pairs. Possible options are:

Hello - SMTP requires that you identify yourself. This option specifies a string to pass as your mail domain. If not given localhost.localdomain will be used.

Host - SMTP host to connect to. It may be a single scalar, as defined for the "PeerAddr" option in IO::Socket::INET, or a reference to an array with hosts to try in turn. The ``host'' method will return the value which was used to connect to the host.

LocalAddr and LocalPort - These parameters are passed directly to IO::Socket to allow binding the socket to a local port.

Timeout - Maximum time, in seconds, to wait for a response from the SMTP server (default: 120)

ExactAddresses - If true the all ADDRESS arguments must be as defined by "addr-spec" in RFC2822. If not given, or false, then Net::SMTP will attempt to extract the address from the value passed.

Debug - Enable debugging information


    $smtp = Net::SMTP->new('mailhost',
                           Hello => 'my.mail.domain'
                           Timeout => 30,
                           Debug   => 1,

    # the same
    $smtp = Net::SMTP->new(
                           Host => 'mailhost',
                           Hello => 'my.mail.domain'
                           Timeout => 30,
                           Debug   => 1,

    # Connect to the default server from Net::config
    $smtp = Net::SMTP->new(
                           Hello => 'my.mail.domain'
                           Timeout => 30,



Unless otherwise stated all methods return either a true or false value, with true meaning that the operation was a success. When a method states that it returns a value, failure will be returned as undef or an empty list.
banner ()
Returns the banner message which the server replied with when the initial connection was made.
domain ()
Returns the domain that the remote SMTP server identified itself as during connection.
hello ( DOMAIN )
Tell the remote server the mail domain which you are in using the EHLO command (or HELO if EHLO fails). Since this method is invoked automatically when the Net::SMTP object is constructed the user should normally not have to call it manually.
host ()
Returns the value used by the constructor, and passed to IO::Socket::INET, to connect to the host.
etrn ( DOMAIN )
Request a queue run for the DOMAIN given.
Attempt SASL authentication.
mail ( ADDRESS [, OPTIONS] )
send ( ADDRESS )
send_or_mail ( ADDRESS )
send_and_mail ( ADDRESS )
Send the appropriate command to the server MAIL, SEND, SOML or SAML. "ADDRESS" is the address of the sender. This initiates the sending of a message. The method "recipient" should be called for each address that the message is to be sent to.

The "mail" method can some additional ESMTP OPTIONS which is passed in hash like fashion, using key and value pairs. Possible options are:

 Size        => <bytes>
 Return      => "FULL" | "HDRS"
 Bits        => "7" | "8" | "binary"
 Transaction => <ADDRESS>
 Envelope    => <ENVID>
 XVERP       => 1

The "Return" and "Envelope" parameters are used for DSN (Delivery Status Notification).

reset ()
Reset the status of the server. This may be called after a message has been initiated, but before any data has been sent, to cancel the sending of the message.
recipient ( ADDRESS [, ADDRESS, [...]] [, OPTIONS ] )
Notify the server that the current message should be sent to all of the addresses given. Each address is sent as a separate command to the server. Should the sending of any address result in a failure then the process is aborted and a false value is returned. It is up to the user to call "reset" if they so desire.

The "recipient" method can also pass additional case-sensitive OPTIONS as an anonymous hash using key and value pairs. Possible options are:

  Notify  => ['NEVER'] or ['SUCCESS','FAILURE','DELAY']  (see below)
  SkipBad => 1        (to ignore bad addresses)

If "SkipBad" is true the "recipient" will not return an error when a bad address is encountered and it will return an array of addresses that did succeed.

  $smtp->recipient($recipient1,$recipient2);  # Good
  $smtp->recipient($recipient1,$recipient2, { SkipBad => 1 });  # Good
  $smtp->recipient($recipient1,$recipient2, { Notify => ['FAILURE','DELAY'], SkipBad => 1 });  # Good
  @goodrecips=$smtp->recipient(@recipients, { Notify => ['FAILURE'], SkipBad => 1 });  # Good
  $smtp->recipient("$recipient,$recipient2"); # BAD

Notify is used to request Delivery Status Notifications (DSNs), but your SMTP/ESMTP service may not respect this request depending upon its version and your site's SMTP configuration.

Leaving out the Notify option usually defaults an SMTP service to its default behavior equivalent to ['FAILURE'] notifications only, but again this may be dependent upon your site's SMTP configuration.

The NEVER keyword must appear by itself if used within the Notify option and ``requests that a DSN not be returned to the sender under any conditions.''

  {Notify => ['NEVER']}

  $smtp->recipient(@recipients, { Notify => ['NEVER'], SkipBad => 1 });  # Good

You may use any combination of these three values 'SUCCESS','FAILURE','DELAY' in the anonymous array reference as defined by RFC3461 (see for more information. Note: quotations in this topic from same.).

A Notify parameter of 'SUCCESS' or 'FAILURE' ``requests that a DSN be issued on successful delivery or delivery failure, respectively.''

A Notify parameter of 'DELAY' ``indicates the sender's willingness to receive delayed DSNs. Delayed DSNs may be issued if delivery of a message has been delayed for an unusual amount of time (as determined by the Message Transfer Agent (MTA) at which the message is delayed), but the final delivery status (whether successful or failure) cannot be determined. The absence of the DELAY keyword in a NOTIFY parameter requests that a ''delayed`` DSN NOT be issued under any conditions.''

  {Notify => ['SUCCESS','FAILURE','DELAY']}

  $smtp->recipient(@recipients, { Notify => ['FAILURE','DELAY'], SkipBad => 1 });  # Good

to ( ADDRESS [, ADDRESS [...]] )
cc ( ADDRESS [, ADDRESS [...]] )
bcc ( ADDRESS [, ADDRESS [...]] )
Synonyms for "recipient".
data ( [ DATA ] )
Initiate the sending of the data from the current message.

"DATA" may be a reference to a list or a list. If specified the contents of "DATA" and a termination string ".\r\n" is sent to the server. And the result will be true if the data was accepted.

If "DATA" is not specified then the result will indicate that the server wishes the data to be sent. The data must then be sent using the "datasend" and "dataend" methods described in Net::Cmd.

expand ( ADDRESS )
Request the server to expand the given address Returns an array which contains the text read from the server.
verify ( ADDRESS )
Verify that "ADDRESS" is a legitimate mailing address.

Most sites usually disable this feature in their SMTP service configuration. Use ``Debug => 1'' option under new() to see if disabled.

help ( [ $subject ] )
Request help text from the server. Returns the text or undef upon failure
quit ()
Send the QUIT command to the remote SMTP server and close the socket connection.


Net::SMTP attempts to DWIM with addresses that are passed. For example an application might extract The From: line from an email and pass that to mail(). While this may work, it is not reccomended. The application should really use a module like Mail::Address to extract the mail address and pass that.

If "ExactAddresses" is passed to the contructor, then addresses should be a valid rfc2821-quoted address, although Net::SMTP will accept accept the address surrounded by angle brackets.

 funny user@domain      WRONG
 "funny user"@domain    RIGHT, recommended
 <"funny user"@domain>  OK





Graham Barr <>  


Copyright (c) 1995-2004 Graham Barr. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.




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