I am using sSMTP with PHP for e-mail sending and it works fine.
The problem is that sSMTP performs the delivery synchronously which adds latency to my PHP scripts, letting the user waiting a little too long.
Is there a way to make it work non-blocking?
(I though of a hack on the shell, to start the sSMTP process on the background or something, and return earlier back to PHP, but I could not make it work.)
Yes use one of the nullmailers which supports queueing or a full MTA instead of ssmtp. While you could write a wrapper around SSMTP, it'll need to fork and setsid to isolate from the calling php process.
This works with sendmail piping. Here is an example of what the data that gets piped looks like
To: to@to.com
Subject: Your Subject Here
X-PHP-Originating-Script: 0:MailSender.class.php
MIME-Version: 1.0
Content-type: text/html; charset=iso-8859-1
From: First Last <noreply@cool.com>
BODY OF EMAIL GOES HERE
Save this script as /usr/sbin/sendmail
#!/bin/bash
# sendmail wrapper for ssmtp to send email asynchronously
TMP=`mktemp`
stdin=$(cat)
echo "$stdin" > $TMP
body=`cat $TMP`
# Create the email and store in file
echo "ssmtp -t <<EOF " > $TMP
echo "$body" >> $TMP
echo "EOF" >> $TMP
echo "rm -f $TMP" >> $TMP
# Send the email
sh $TMP &
You can use gearman or other similar techniques do make blocking things asynchronously. See http://www.phpclasses.org/blog/post/108-Distributing-PHP-processing-with-Gearman.html
Ok, I figured it out! Using the script command we can write a wrapper:
#!/bin/sh
script -q -c "/usr/sbin/ssmtp $*" /dev/null