custom-sendmail-routine

<chapter id="DefineCustomSendmailRoutine">

	<chapterinfo>
		<title>Define Custom Sendmail Routine</title>
		<titleabbrev>customsendmail</titleabbrev>

		<keywordset>
			<keyword>custom</keyword>
			<keyword>send</keyword>
			<keyword>mail</keyword>
			<keyword>routine</keyword>
			<keyword>delay</keyword>
		</keywordset>

		<authorgroup>
			<author>
				<firstname>Mike</firstname>
				<surname>Heins</surname>
				<affiliation>
					<email>mheins@perusion.net</email>
				</affiliation>
			</author>
		</authorgroup>


	</chapterinfo>

	<sect1 id='customsendmail_introduction'>
		<title>Introduction</title>
		<para>
		HOW-TO version: $Id: custom-sendmail-routine,v 1.3 2004-11-12 22:26:26 docelic Exp $
		</para>
		<para>
		Someone <ulink url="http://www.icdevgroup.org/pipermail/interchange-users/2004-July/039811.html">was wondering</ulink> how to optimize the order processing on a busy site. It was observed that about once in every ten times, the <filename>etc/mail_receipt</filename> takes a few <emphasis>extra</emphasis> seconds before it's mailed out.
		</para>
		<para>
		The delay occured because in the code used, the <option>SendMailProgram</option> ran in foreground so the ordering process "stalled" for a few seconds (or at least that's how the average customer saw it). The critical section was reduced to:
		</para>

		<screen>
<![CDATA[
[email to="[scratch to_email], __MAIL_RECEIPT_CC__"
       subject="__COMPANY__ Order #[value mv_order_number]: [scratch subject_end]"
       from=|"__COMPANY__ Order Confirmation" <orders at company.com>| ]

... email contents ...

[/email]
]]>
		</screen>
	</sect1>

	<sect1 id='customsendmail_solution'>
		<title>Solution</title>
		<para>
		To eliminate this "delay", you could use a custom script that accepts the message on standard input (STDIN), and then calls <application>Sendmail</application> in the background.
		</para> <para>
		Save the script with the following contents to <filename>/usr/local/bin/sendmail-bg</filename>:
		</para>

		<programlisting>
<![CDATA[
#!/usr/bin/perl

#use strict;
#use warnings;
use File::Temp;

my $basedir = '/tmp/sendmail';
my $sendmail = '/usr/sbin/sendmail -t';
umask 2;

mkdir $basedir unless -d $basedir;
my $tmp = File::Temp->new( DIR => $basedir );
my $tmpnam = $tmp->filename;

open OUT, "> $tmpnam" or die "Cannot create $tmpnam: $!\n";
my $cmdline = join " ", $sendmail, '<', $tmpnam, '&';
while(<>) { print OUT $_; }
close OUT;

system($cmdline);

if($?) { die "Failed to fork sendmail: $!\n" }

]]>
		</programlisting>

	<para>
	And of course, don't forget to add/modify the <option>SendMailProgram</option> directive:
	</para>

	<programlisting>
SendMailProgram /usr/local/bin/sendmail-bg
	</programlisting>

	</sect1>

</chapter>