NAME¶
Email::Sender::Manual::QuickStart - how to start using Email::Sender right now
VERSION¶
version 0.110005
QUICK START¶
Let's Send Some Mail!¶
No messing around, let's just send some mail.
use strict;
use Email::Sender::Simple qw(sendmail);
use Email::Simple;
use Email::Simple::Creator;
my $email = Email::Simple->create(
header => [
To => '"Xavier Q. Ample" <x.ample@example.com>',
From => '"Bob Fishman" <orz@example.mil>',
Subject => "don't forget to *enjoy the sauce*",
],
body => "This message is short, but at least it's cheap.\n",
);
sendmail($email);
That's it. Your message goes out into the internet and tries to get delivered to
"x.ample@example.com".
In the example above, $email could be an Email::Simple object, a MIME::Entity, a
string containing an email message, or one of several other types of input. If
"Email::Abstract" can understand a value, it can be passed to
Email::Sender::Simple. Email::Sender::Simple tries to make a good guess about
how to send the message. It will usually try to use the
sendmail
program on unix-like systems and to use SMTP on Windows. You can specify a
transport, if you need to, but normally that shouldn't be an issue. (See
"Picking a Transport", though, for more information.)
Also note that we imported and used a "sendmail" routine in the
example above. This is exactly the same as saying:
Email::Sender::Simple->send($email);
...but it's a lot easier to type. You can use either one.
envelope information
We didn't have to tell Email::Sender::Simple where to send the message. If you
don't specify recipients, it will use all the email addresses it can find in
the
To and
Cc headers by default. It will use Email::Address to
parse those fields. Similarly, if no sender is specified, it will use the
first address found in the
From header.
In most email transmission systems, though, the headers are not by necessity
tied to the addresses used as the sender and recipients. For example, your
message header might say "From: mailing-list@example.com" while your
SMTP client says "MAIL FROM:<verp-1234@lists.example.com>".
This is a powerful feature, and is necessary for many email application. Being
able to set those distinctly is important, and Email::Sender::Simple lets you
do this:
sendmail($email, { to => [ $to_1, $to_2 ], from => $sender });
in case of error
When the message is sent successfully (at least on to its next hop),
"sendmail" will return a true value -- specifically, an
Email::Sender::Success object. This object only rarely has much use. What's
more useful is what happens if the message can't be sent.
If there is an error sending the message, an exception will be thrown. It will
be an object belonging to the class Email::Sender::Failure. This object will
have a "message" attribute describing the nature of the failure.
There are several specialized forms of failure, like
Email::Sender::Failure::Multi, which is thrown when more than one error is
encountered when trying to send. You don't need to know about these to use
Email::Sender::Simple, though. All you need to know is that
"sendmail" returns true on success and dies on failure.
If you'd rather not have to catch exceptions for failure to send mail, you can
use the "try_to_send" method, which can be imported as
"try_to_sendmail". This method will return just false on failure to
send mail.
For example:
Email::Sender::Simple->try_to_send($email, { ... });
use Email::Sender::Simple qw(try_to_sendmail);
try_to_sendmail($email, { ... });
Some Email::Sender transports can signal success if some, but not all,
recipients could be reached. Email::Sender::Simple does its best to ensure
that this never happens. When you are using Email::Sender::Simple, mail should
either be sent or not. Partial success should never occur.
Picking a Transport¶
passing in your own transport
If Email::Sender::Simple doesn't pick the transport you want, or if you have
more specific needs, you can specify a transport in several ways. The simplest
is to build a transport object and pass it in. You can read more about
transports elsewhere. For now, we'll just assume that you need to send mail
via SMTP on an unusual port. You can send mail like this:
my $transport = Email::Sender::Transport::SMTP->new({
host => 'smtp.example.com',
port => 2525,
});
sendmail($email, { transport => $transport });
Now, instead of guessing at what transport to use, Email::Sender::Simple will
use the one you provided. This transport will have to be specified for each
call to "sendmail", so you might want to look at other options,
which follow.
specifying transport in the environment
If you have a program that makes several calls to Email::Sender::Simple, and you
need to run this program using a different mailserver, you can set environment
variables to change the default. For example:
$ export EMAIL_SENDER_TRANSPORT=SMTP
$ export EMAIL_SENDER_TRANSPORT_host=smtp.example.com
$ export EMAIL_SENDER_TRANSPORT_port=2525
$ perl your-program
It is important to note that if you have set the default transport by using the
environment,
no subsequent "transport" args to
"sendmail" will be respected. If you set
the default transport via the environment, that's it. Everything will use that
transport. (Also, note that while we gave the host and port arguments above in
lower case, the casing of arguments in the environment is flattened to support
systems where environment variables are of a fixed case. So,
"EMAIL_SENDER_TRANSPORT_PORT" would also work.
This is extremely valuable behavior, as it allows you to audit every message
that would be sent by a program by running something like this:
$ export EMAIL_SENDER_TRANSPORT=Maildir
$ perl your-program
In that example, any message sent via Email::Sender::Simple would be delivered
to a maildir in the current directory.
subclassing to change the default transport
If you want to use a library that will behave like Email::Sender::Simple but
with a different default transport, you can subclass Email::Sender::Simple and
replace the "build_default_transport" method.
Testing¶
Email::Sender::Simple makes it very, very easy to test code that sends email.
The simplest way is to do something like this:
use Test::More;
BEGIN { $ENV{EMAIL_SENDER_TRANSPORT} = 'Test' }
use YourCode;
YourCode->run;
my @deliveries = Email::Sender::Simple->default_transport->deliveries;
Now you've got an array containing every delivery performed through
Email::Sender::Simple, in order. Because you set the transport via the
environment, no other code will be able to force a different transport.
When testing code that forks, Email::Sender::Transport::SQLite can be used to
allow every child process to deliver to a single, easy to inspect destination
database.
Hey, where's my Bcc support?¶
A common question is "Why doesn't Email::Sender::Simple automatically
respect my Bcc header?" This is often combined with, "Here is a
patch to 'fix' it." This is not a bug or oversight. Bcc is being ignored
intentionally for now because simply adding the Bcc addresses to the message
recipients would not produce the usually-desired behavior.
For example, here is a set of headers:
From: sender@example.com
To: to_rcpt@example.com
Cc: cc_rcpt@example.com
Bcc: the_boss@example.com
In this case, we'd expect the message to be delivered to three people: to_rcpt,
cc_rcpt, and the_boss. This is why it's often suggested that the Bcc header
should be a source for envelope recipients. In fact, though, a message with a
Bcc header should probably be delivered
only to the Bcc recipients. The
"B" in Bcc means "blind." The other recipients should not
see who has been Bcc'd. This means you want to send
two messages: one
to to_rcpt and cc_rcpt, with no Bcc header present; and another to the_boss
only, with the Bcc header.
If you just pick up Bcc addresses as
recipients, everyone will see who was Bcc'd.
Email::Sender::Simple promises to send messages atomically. That is: it won't
deliver to only some of the recipients, and not to others. That means it can't
automatically detect the Bcc header and make two deliveries. There would be a
possibility for the second to fail after the first succeeded, which would
break the promise of a pure failure or success.
The other strategy for dealing with Bcc is to remove the Bcc header from the
message and then inject the message with an envelope including the Bcc
addresses. The envelope information will not be visible to the final
recipients, so this is safe. Unfortunately, this requires modifying the
message, and Email::Sender::Simple should not be altering the mutable email
object passed to it. There is no "clone" method on Email::Abstract,
so it cannot just build a clone and modify that, either. When such a method
exists, Bcc handling may be possible.
Example Bcc Handling
If you want to support the Bcc header now, it is up to you to deal with how you
want to munge the mail and inject the (possibly) munged copies into your
outbound mailflow. It is not reasonable to suggest that Email::Sender::Simple
do this job.
Example 1: Explicitly set the envelope recipients for Bcc recipients
Create the email without a Bcc header, send it to the Bcc users explicitly and
then send it to the To/Cc users implicitly.
my $message = create_email_mime_msg; # <- whatever you do to get the message
$message->delete_header('bcc'); # delete the Bcc header before sending
sendmail($message, { to => $rcpt' }); # send to explicit Bcc address
sendmail($message); # and then send as normal
Example 2: Explicitly set the envelope recipients for all recipients
You can make a single call to "sendmail" by pulling all the recipient
addresses from the headers yourself and specifying all the envelope recipients
once. Again, delete the Bcc header before the message is sent.
SEE ALSO¶
This is awesome! Where can I learn more?¶
Have a look at Email::Sender::Manual, where all the manual's documents are
listed. You can also look at the documentation for Email::Sender::Simple and
the various Email::Sender::Transport classes.
AUTHOR¶
Ricardo Signes <rjbs@cpan.org>
COPYRIGHT AND LICENSE¶
This software is copyright (c) 2012 by Ricardo Signes.
This is free software; you can redistribute it and/or modify it under the same
terms as the Perl 5 programming language system itself.