NAME¶
Email::MIME::CreateHTML - Multipart HTML Email builder
SYNOPSIS¶
use Email::MIME::CreateHTML;
my $email = Email::MIME->create_html(
header => [
From => 'my@address',
To => 'your@address',
Subject => 'Here is the information you requested',
],
body => $html,
text_body => $plain_text
);
use Email::Send;
my $sender = Email::Send->new({mailer => 'SMTP'});
$sender->mailer_args([Host => 'smtp.example.com']);
$sender->send($email);
DESCRIPTION¶
This module allows you to build HTML emails, optionally with a text-only
alternative and embedded media objects. For example, an HTML email with an
alternative version in plain text and with all the required images contained
in the mail.
The HTML content is parsed looking for embeddable media objects. A resource
loading routine is used to fetch content from those URIs and replace the URIs
in the HTML with CIDs. The default resource loading routine is deliberately
conservative, only allowing resources to be fetched from the local filesystem.
It's possible and relatively straightforward to plug in a custom resource
loading routine that can resolve URIs using a broader range of protocols. An
example of one using LWP is given later in the "COOKBOOK".
The MIME structure is then assembled, embedding the content of the resources
where appropriate. Note that this module does not send any mail, it merely
does the work of building the appropriate MIME message. The message can be
sent with Email::Send or any other mailer that can be fed a string
representation of an email message.
Mail Construction¶
The mail construction is compliant with rfc2557.
HTML, no embedded objects (images, flash, etc), no text alternative
text/html
HTML, no embedded objects, with text alternative
multipart/alternative
text/plain
text/html
HTML with embedded objects, no text alternative
multipart/related
text/html
embedded object one
embedded object two
...
HTML with embedded objects, with text alternative
multipart/alternative
text/plain
multipart/related
text/html
embedded object one
embedded object two
...
METHODS¶
There is only one method, which is installed into the Email::MIME package:
- Email::MIME->create_html(%parameters)
- This method creates an Email::MIME object from a set of named parameters.
Of these the "header" and "body" parameters are
mandatory and all others are optional. See the "PARAMETERS"
section for more information.
LOW-LEVEL API¶
Email::MIME::CreateHTML also defines a lower-level interface of 3 building-block
routines that you can use for finer-grain construction of HTML mails. These
may be optionally imported:
use Email::MIME::CreateHTML qw(embed_objects parts_for_objects build_html_mail);
- ($modified_html, $cid_mapping) = embed_objects($html, \%options)
- This parses the HTML and replaces URIs in the embed list with a CID. The
modified HTML and CID to URI mapping is returned. Relevant parameters are:
embed
inline_css
base
object_cache
resolver
The meanings and defaults of these parameters are explained below.
- @mime_parts = parts_for_objects($cid_mapping, \%options)
- This creates a list of Email::MIME parts for each of the objects in the
supplied CID mapping. Relevant options are:
base
object_cache
resolver
The meanings and defaults of these parameters are explained below.
- $email = build_html_email(\@headers, $html, \%body_attributes,
\@html_mime_parts, $plain_text_mime)
- The assembles a ready-to-send Email::MIME object (that can be sent with
Email::Send).
PARAMETERS¶
- header => list
- A list reference containing a set of headers to be created. If no Date
header is specified, one will be provided for you based on the
gmtime() of the local machine.
- body => scalar
- A scalar value holding the HTML message body.
- body_attributes => hash reference
- This is passed as the attributes parameter to the "create"
method (supplied by "Email::MIME::Creator") that creates the
html part of the mail. The body content-type will be set to
"text/html" unless it is overidden here.
- embed => boolean
- Attach relative images and other media to the message. This is enabled by
default. The module will attempt to embed objects defined by
"embed_elements". Note that this option only affects the parsing
of the HTML and will not affect the "objects" option.
The object's URI will be rewritten as a Content ID.
- embed_elements => reference to hash of hashes with boolean
values
- The set of elements that you want to be embedded. Defaults to the
%Email::MIME::CreateHTML::EMBED package global. This should be a data
structure of the form:
embed_elements => {
$elementname_1 => {$attrname_1 => $boolean_1},
$elementname_2 => {$attrname_2 => $boolean_2},
...
}
i.e. resource will be embedded if
"$embed_elements->{$elementname}->{$attrname}" is
true.
- resolver => object
- If a resolver is supplied this will be used to fetch the resources that
are embedded as MIME objects in the email. If no resolver is given the
default behaviour is to choose the best available resolver to read $uri
with any $base value prefixed. Resources fetched using the resolver will
be cached if an "object_cache" is supplied.
- base => scalar
- This must be a filepath or a URI.
If "embed" is true (the default) then "base" will be
used when fetching the objects.
Examples of good bases:
./local/images
/home/somewhere/images
http://mywebserver/images
- inline_css => boolean
- Inline any CSS external CSS files referenced through link elements.
Enabled by default. Some mail clients will only interpret css if it is
inlined.
- objects => hash reference
- A reference to a hash of external objects. Keys are Content Ids and the
values are filepaths or URIs used to fetch the resource with the resolver.
We use "MIME::Types" to derive the type from the file extension.
For example in an HTML mail you would use the file keyed on
'12345678@bbc.co.uk' like "<img
src="cid:12345678@bbc.co.uk" alt="a test"
width="20" height="20" />"
- object_cache => cache object
- A cache object can be supplied to cache external resources such as images.
This must support the following interface:
$o = new ...
$o->set($key, $value)
$value = $o->get($key)
Both the Cache and Cache::Cache distributions on CPAN conform to this.
- text_body => scalar
- A scalar value holding the contents of an additional plain text
message body.
- text_body_attributes => hash reference
- This is passed as the attributes parameter to the "create"
method (supplied by "Email::MIME::Creator") that creates the
plain text part of the mail. The body Content-Type will be set to
"text/plain" unless it is overidden here.
GLOBAL VARIABLES¶
- %Email::MIME::CreateHTML::EMBED
- This is the default set of elements (and the relevant attributes that
point at a resource) that will be embedded. The for this is:
'bgsound' => {'src'=>1},
'body' => {'background'=>1},
'img' => {'src'=>1},
'input' => {'src'=>1},
'table' => {'background'=>1},
'td' => {'background'=>1},
'th' => {'background'=>1},
'tr' => {'background'=>1}
You can override this using the "embed_elements" parameter.
COOKBOOK¶
The basics¶
This builds an HTML email:
my $email = Email::MIME->create_html(
header => [
From => 'my@address',
To => 'your@address',
Subject => 'My speedy HTML',
],
body => $html
);
If you want a plaintext alternative, include the "text_body" option:
my $email = Email::MIME->create_html(
header => [
From => 'my@address',
To => 'your@address',
Subject => 'Here is the information you requested',
],
body => $html,
text_body => $plain_text #<--
);
If you want your images to remain as links (rather than be embedded in the
email) disable the "embed" option:
my $email = Email::MIME->create_html(
header => [
From => 'my@address',
To => 'your@address',
Subject => 'My speedy HTML',
],
body => $html,
embed => 0 #<--
);
Optimising out HTML parsing¶
By default, the HTML is parsed to look for objects and stylesheets that need
embedding. If you are controlling the construction of the HTML yourself, you
can use Content Ids as the URIs within your HTML and then pass in a set of
objects to associate with those Content IDs:
my $html = qq{
<html><head><title>My Document</title></head><body>
<p>Here is a picture:</p><img src="cid:some_image_jpg@bbc.co.uk">
</body></html>
};
You then need to create a mapping of the Content IDs to object filenames:
my %objects = (
"some_image_jpg@bbc.co.uk" => "/var/html/some_image.jpg"
);
Finally you need to disable both the "embed" and
"inline_css" options to turn off HTML parsing, and pass in your
mapping:
my $quick_to_assemble_mime = Email::MIME->create_html(
header => [
From => 'my@address',
To => 'your@address',
Subject => 'My speedy HTML',
],
body => $html,
embed => 0, #<--
inline_css => 0, #<--
objects => \%objects #<--
);
Preprocessing templates
If you have for example a personalised newsletter where your HTML will vary
slightly from one email to the next, but you don't want to re-parse the HTML
each time to re-fetch and attach objects, you can use the
"embed_objects" function to pre-process the template, converting
URIs into CIDs:
use Email::MIME::CreateHTML qw(embed_objects);
my ($preproc_tmpl_content, $cid_mapping) = embed_objects($tmpl_content);
You can then reuse this and the CID mapping:
my $template = compile_template($preproc_tmpl_content);
foreach $newsletter (@newsletters) {
#Do templating
my $html = $template->process($newsletter);
#Build MIME structure
my $mime = Email::MIME->create_html(
header => [
From => $reply_address,
To => $newsletter->address,
Subject => 'Weekly newsletter',
],
body => $html,
embed => 0, #Already done
inline_css => 0, #Already done
objects => $cid_mapping #Here's one we prepared earlier
);
#Send email
send_email($mime);
}
Note that one caveat with this approach is that all possible images that might
be used in the template will be attached to the email. Depending on your
template logic, it may be that some are never actually referenced from within
the email (e.g. if an image is conditionally displayed) so this may create
unnecessarily large emails.
Plugging in a custom resource resolver¶
A custom resource resolver can be specified by passing your own object to
resolver:
my $mime = Email::MIME->create_html(
header => [
From => 'my@address',
To => 'your@address',
Subject => 'Here is the information you requested',
],
body => $html,
base => 'http://internal.foo.co.uk/images/',
resolver => new MyResolver, #<--
);
The object needs to have the following API:
package MyResolver;
sub new {
my ($self, $options) = @_;
my $base_uri = $options->{base};
#... YOUR CODE HERE ... (probably want to stash $base_uri in $self)
}
sub get_resource {
my ($self, $uri) = @_;
my ($content,$filename,$mimetype,$xfer_encoding);
#... YOUR CODE HERE ...
return ($content,$filename,$mimetype,$xfer_encoding);
}
where:
$uri is the URI of the object we are embedding (taken from the markup or passed in via the CID mapping)
$base_uri is base URI used to resolve relative URIs
$content is a scalar containing the contents of the file
$filename is used to set the name attribute of the Email::MIME object
$mimetype is used to set the content_type attribute of the Email::MIME object
$xfer_encoding is used to set the encoding attribute of the Email::MIME object
(note this is the suitable transfer encoding NOT a character encoding)
Plugging in different types of object cache¶
You can use a cache from the Cache::Cache distribution:
use Cache::MemoryCache;
my $mime = Email::MIME->create_html(
header => \@headers,
body => $html,
object_cache => new Cache::MemoryCache( {
'namespace' => 'MyNamespace',
'default_expires_in' => 600
} )
);
Or a cache from the Cache distribution:
use Cache::File;
my $mime = Email::MIME->create_html(
header => \@headers,
body => $html,
object_cache => Cache::File->new(
cache_root => '/tmp/mycache',
default_expires => '600 sec'
)
);
Alternatively you can roll your own. You just need to define an object with get
and set methods:
my $mime = Email::MIME->create_html(
header => \@headers,
body => $html,
object_cache => new MyCache()
);
package MyCache;
our %Cache;
sub new {return bless({}, shift())}
sub get {return $Cache{shift()}}
sub set {$Cache{shift()} = shift()}
1;
SEE ALSO¶
Perl Email Project <
http://pep.pobox.com>
Email::Simple, Email::MIME, Email::Send, Email::MIME::Creator
TODO¶
Maybe add option to control the order that the text + html parts appear in the
MIME message.
AUTHOR¶
Tony Hennessy and Simon Flack with cookbook + some refactoring by John Alden
<cpan _at_ bbc _dot_ co _dot_ uk> with additional contributions by
Ricardo Signes <rjbs@cpan.org> and Henry Van Styn
<vanstyn@cpan.org>
COPYRIGHT¶
(c) BBC 2005,2006. This program is free software; you can redistribute it and/or
modify it under the GNU GPL.
See the file COPYING in this distribution, or
http://www.gnu.org/licenses/gpl.txt