NAME

POE::Component::Server::SimpleSMTP - A simple to use POE SMTP Server.

VERSION

version 1.52

SYNOPSIS

# A simple SMTP Server
use strict;
use POE;
use POE::Component::Server::SimpleSMTP;

my $hostname = 'mymailserver.local';
my $relay; # specify a smart 'relay' server if required

POE::Component::Server::SimpleSMTP->spawn(
hostname => $hostname,
relay => $relay,
);

$poe_kernel->run();
exit 0;

DESCRIPTION

POE::Component::Server::SimpleSMTP is a POE component that provides an
ease to use, but fully extensible SMTP mail server, that is reasonably
compliant with RFC 2821 http://www.faqs.org/rfcs/rfc2821.html.

In its simplest form it provides SMTP services, accepting mail from
clients and either relaying the mail to a smart host for further
delivery or delivering the mail itself by querying DNS MX records.

One may also disable simple functionality and implement one's own SMTP
handling and mail queuing. This can be done via a POE state interface
or via POE::Component::Pluggable plugins.

CONSTRUCTOR

spawn

Takes a number of optional arguments:

'alias', set an alias on the component;
'address', bind the listening socket to a particular address;
'port', listen on a particular port, default is 25;
'options', a hashref of POE::Session options;
'hostname', the name that the server will identify as in 'EHLO';
'version', change the version string reported in 220 responses;
'relay', specify a 'smart host' to send received mail to, default is
to deliver direct after determining MX records;
'relay_auth', ESMTP Authentication to use, currently only PLAIN is supported, which is the default;
'relay_user', the username required for authenticated relay;
'relay_pass', the password required for authenticated relay;
'time_out', alter the timeout period when sending emails, default 300 seconds;
'maxrelay', maximum number of concurrent outgoing emails, defaults to 5;
'domains', an arrayref of domain/hostnames that we will accept mail for;
'origin', set to a true value to enable the stripping of Received headers;

These optional arguments can be used to enable your own SMTP
handling:

'simple', set this to a false value and the component will no
longer handle SMTP processing;
'handle_connects', set this to a false value to stop the component sending
220 responses on client connections;

In simple mode one may also specify recipient handlers. These are
regular expressions that are applied to each recipient of a recieved
email. If a recipient matches the handler, it is removed from the
process queue and dispatched instead to indicated session/event
combo.

'handlers', an arrayref containing hashrefs. Each hashref should contain the keys:

'match', a regexp to apply;
'session', The session to send the email to;
'event', The event to trigger;

You may also enable DNSBL lookups of connecting clients with the
following options:

'dnsbl_enable', set to a true value to enable DNSBL support;
'dnsbl', set to a DNSBL to query, default is zen.spamhaus.org;

DNSBL support uses POE::Component::Client::DNSBL to make blacklist
queries for each connecting client. If a client is found in the
blacklist, any further interaction with the client is denied.

You may also enable sender verification, this does a simple MX DNS
lookup on the domain of the email sender. If there is no MX domain
record (ie. an NXDOMAIN) then a 550 is issued. In the case of a
SERVFAIL, a 451 is issued. In both cases the email transaction is
cancelled.

'sender_verify', set to a true value to enable sender verification;

See OUTPUT EVENTS below for information on what a handler event
contains.

Returns a POE::Component::Server::SimpleSMTP object.

METHODS

session_id

Returns the POE::Session ID of the component.

shutdown

Terminates the component. Shuts down the listener and disconnects
connected clients.

send_event

Sends an event through the component's event handling system.

send_to_client

Send some output to a connected client. First parameter must be a
valid client id. Second parameter is a string of text to send.

data_mode

Takes one argument a valid client ID. Switches the client connection
to data mode for receiving an mail message. This should be done in
response to a valid DATA command from a client if you are doing your
own SMTP handling.

You will receive an 'smtpd_data' event when the client has finished
sending data. See below.

Optionally, you may supply a filehandle as a second argument. Any
data received from the client will be written to the filehandle. You
will receive an 'smtpd_data_fh' event when the client has finished
sending data.

getsockname

Access to the POE::Wheel::SocketFactory method of the underlying
listening socket.

get_handlers

Returns an arrayref of the current handlers.

set_handlers

Accepts an arrayref of handler hashrefs ( see spawn() for details ).

mail_queue

Returns a list of hashrefs relating to items in the current mail
queue ( when in simple mode ).

pause_queue

Pauses the processing of the mail queue. Any currently processing
emails will be allowed to finish.

resume_queue

Resumes the processing of the mail queue.

paused

Indicates whether the mail queue is paused or not.

cancel_message

Takes one mandatory parameter a msg_id to remove from the mail queue.

start_listener

Takes no arguments, start the socket listener if it has stopped for
any reason. Will fail if the listener is already erm listening.

enqueue

Takes one argument, a hashref with the following keys and values.
Enqueues the item and requests that the mail queue be processed.
Returns undef on failure or 1 on success.

'from', the email address of the sender (required);
'rcpt', an arrayref of the email recipients (required);
'msg', string representation of the email headers and body (required);
'ts', the unix time representation of the time the email was received (default is now);
'uid', the Message-ID (default is to generate one for you);

INPUT EVENTS

These are events that the component will accept:

Takes N arguments: a list of event names that your session wants to
listen for, minus the 'smtpd_' prefix, ( this is similar to
POE::Component::IRC ).

Registering for 'all' will cause it to send all SMTPD-related events
to you; this is the easiest way to handle it.

unregister

Takes N arguments: a list of event names which you don't want to
receive. If you've previously done a 'register' for a particular
event which you no longer care about, this event will tell the SMTPD
to stop sending them to you. (If you haven't, it just ignores you. No
big deal).

shutdown

Terminates the component. Shuts down the listener and disconnects
connected clients.

send_event

Sends an event through the component's event handling system.

send_to_client

Send some output to a connected client. First parameter must be a
valid client ID. Second parameter is a string of text to send.

start_listener

Takes no arguments, start the socket listener if it has stopped for
any reason. Will fail if the listener is already erm listening.

OUTPUT EVENTS

The component sends the following events to registered sessions:

smtpd_registered

This event is sent to a registering session. ARG0 is
POE::Component::Server::SimpleSMTP object.

smtpd_listener_failed

Generated if the component cannot either start a listener or there is
a problem accepting client connections. ARG0 contains the name of the
operation that failed. ARG1 and ARG2 hold numeric and string values
for $!, respectively.

smtpd_connection

Generated whenever a client connects to the component. ARG0 is the
client ID, ARG1 is the client's IP address, ARG2 is the client's TCP
port. ARG3 is our IP address and ARG4 is our socket port.

If 'handle_connects' is true ( which is the default ), the component
will automatically send a 220 SMTP response to the client.

smtpd_disconnected

Generated whenever a client disconnects. ARG0 is the client ID.

smtpd_cmd_*

Generated for each SMTP command that a connected client sends to us.
ARG0 is the client ID. ARG1 .. ARGn are any parameters that are sent
with the command. Check the RFC http://www.faqs.org/rfcs/rfc2821.html
for details.

If simple is true ( which is the default ), the component deals with
client commands itself.

smtpd_data

Generated when a client sends an email.

ARG0 will be the client ID;
ARG1 an arrayref of lines sent by the client, stripped of CRLF line endings;

If simple is true ( which is the default ), the component will deal
with receiving data from the client itself.

smtpd_data_fh

Generated when a client sends an email and a filehandle has been
provided.

ARG0 will be the client ID;

If simple is true ( which is the default ), the component will deal
with receiving data from the client itself.

smtpd_dnsbl

Generated when a DNSBL lookup is completed, in simple mode.

ARG0 will be the client ID;
ARG1 will be the response sent to the client, either a 220 or 554;
ARG2 will be a hashref with the following keys:

'response', the status returned by the DNSBL, it will be NXDOMAIN if the address given was okay;
'reason', if an address is blacklisted, this may contain the reason;
'error', if something goes wrong with the DNS lookup the error string will be contained here;
'dnsbl', the DNSBL that was used for this request;

smtpd_fverify

Generated when a sender verification fails, in simple mode.

ARG0 will be the client ID;
ARG1 will be the response sent to the client;
ARG2 will be the DNS error reason;

In simple mode these events will be generated:

smtpd_message_queued

Generated whenever a mail message is queued.

ARG0 is the client ID;
ARG1 is the mail from address;
ARG2 is an arrayref of recipients;
ARG3 is the email unique idenitifer;
ARG4 is the number of lines of the message;
ARG5 is the subject line of the message, if applicable

smtpd_send_success

Generated whenever a mail message is successfully delivered.

ARG0 is the email unique identifier;

smtpd_send_failed

Generated whenever a mail message is unsuccessfully delivered. This
can be for a variety of reasons. The poco will attempt to resend the
message on non-fatal errors ( such as an explicit denial of delivery
by the SMTP peer ), for up to 4 days.

ARG0 is the email unique identifier;
ARG1 is a hashref as returned by POE::Component::Client::SMTP via 'SMTP_Failure'

Handler events are generated whenever a recipient matches a given
regexp. ARG0 will contain a hashref representing the email item with
the following keys:

'uid', the Message-ID;
'from', the email address of the sender;
'rcpt', an arrayref of the email recipients;
'msg', string representation of the email headers and body;
'ts', the unix time representation of the time the email was received;

PLUGINS

POE::Component::Server::SimpleSMTP utilises POE::Component::Pluggable
to enable a POE::Component::IRC type plugin system.

PLUGIN HANDLER TYPES

There are two types of handlers that can registered for by plugins,
these are

SMTPD

These are the 'smtpd_' prefixed events that are generated. In a
handler arguments are passed as scalar refs so that you may mangle
the values if required.

SMTPC

These are generated whenever a response is sent to a client. Again,
any arguments passed are scalar refs for manglement. There is really
on one type of this handler generated 'SMTPC_response'

PLUGIN EXIT CODES

Plugin handlers should return a particular value depending on what
action they wish to happen to the event. These values are available as
constants which you can use with the following line:

use POE::Component::Server::SimpleSMTP::Constants qw(:ALL);

The return values have the following significance:

SMTPD_EAT_NONE

This means the event will continue to be processed by remaining
plugins and finally, sent to interested sessions that registered for
it.

SMTP_EAT_CLIENT

This means the event will continue to be processed by remaining
plugins but it will not be sent to any sessions that registered for
it. This means nothing will be sent out on the wire if it was an
SMTPC event, beware!

SMTPD_EAT_PLUGIN

This means the event will not be processed by remaining plugins, it
will go straight to interested sessions.

SMTPD_EAT_ALL

This means the event will be completely discarded, no plugin or
session will see it. This means nothing will be sent out on the wire
if it was an SMTPC event, beware!

PLUGIN METHODS

The following methods are available:

pipeline

Returns the POE::Component::Pluggable::Pipeline object.

plugin_add

Accepts two arguments:

The alias for the plugin
The actual plugin object

The alias is there for the user to refer to it, as it is possible to
have multiple plugins of the same kind active in one
POE::Component::Server::SimpleSMTP object.

This method goes through the pipeline's push() method.

This method will call $plugin->plugin_register( $nntpd )

Returns the number of plugins now in the pipeline if plugin was
initialized, undef if not.

plugin_del

Accepts one argument:

The alias for the plugin or the plugin object itself

This method goes through the pipeline's remove() method.

This method will call $plugin->plugin_unregister( $nntpd )

Returns the plugin object if the plugin was removed, undef if not.

plugin_get

Accepts one argument:

The alias for the plugin

This method goes through the pipeline's get() method.

Returns the plugin object if it was found, undef if not.

plugin_list

Has no arguments.

Returns a hashref of plugin objects, keyed on alias, or an empty list
if there are no plugins loaded.

plugin_order

Has no arguments.

Returns an arrayref of plugin objects, in the order which they are
encountered in the pipeline.

plugin_register

Accepts the following arguments:

The plugin object
The type of the hook, SMTPD or SMTPC
The event name(s) to watch

The event names can be as many as possible, or an arrayref. They
correspond to the prefixed events and naturally, arbitrary events
too.

You do not need to supply events with the prefix in front of them,
just the names.

It is possible to register for all events by specifying 'all' as an
event.

Returns 1 if everything checked out fine, undef if something's
seriously wrong

plugin_unregister

Accepts the following arguments:

The plugin object
The type of the hook, SMTPD or SMTPC
The event name(s) to unwatch

The event names can be as many as possible, or an arrayref. They
correspond to the prefixed events and naturally, arbitrary events
too.

You do not need to supply events with the prefix in front of them,
just the names.

It is possible to register for all events by specifying 'all' as an
event.

Returns 1 if all the event name(s) was unregistered, undef if some
was not found.

PLUGIN TEMPLATE

The basic anatomy of a plugin is:

package Plugin;

# Import the constants, of course you could provide your own
# constants as long as they map correctly.
use POE::Component::Server::SimpleSMTP::Constants qw( :ALL );

# Our constructor
sub new {
...
}

# Required entry point for plugins
sub plugin_register {
my( $self, $smtpd ) = @_;

# Register events we are interested in
$smtpd->plugin_register( $self, 'SMTPD', qw(all) );

# Return success
return 1;
}

# Required exit point for pluggable
sub plugin_unregister {
my( $self, $smtpd ) = @_;

# Pluggable will automatically unregister events for the plugin

# Do some cleanup...

# Return success
return 1;
}

sub _default {
my( $self, $smtpd, $event ) = splice @_, 0, 3;

print "Default called for $event\n";

# Return an exit code
return SMTPD_EAT_NONE;
}

CAVEATS

This module shouldn't be used as is, as a production SMTP server, as
the message queue is implemented in memory. *ouch*

TODO

Design a better message queue so that messages are stored on disk.

KUDOS

George Nistoric for POE::Component::Client::SMTP and
POE::Filter::Transparent::SMTP.

Rocco Caputo for POE::Component::Client::DNS