TranscendLinux.com

Linux:
(2.6 kernel only)
Check vm.swappiness: sysctl -A|grep swap
The default is 60, which is generally too high... if it is still the default, set it to 20:

sysctl -w vm.swappiness=20
echo "vm.swappiness = 20" >> /etc/sysctl.conf

Here is a script you can use to verify php mail is functioning... you need to change the to and from address variables appropriately.

$to_address="your@email.com";
$from_address="user@server.com";

$body="Test message";

$headers = "From: $from_address \r\n";
$headers.= "Content-Type: text/plain; charset=ISO-8859-1 ";
$headers .= "MIME-Version: 1.0 ";

Upgrading to PHP 5 can create some unfortunate issues with Horde webmail. While the version of Horde provided by Plesk is technically PHP 5 compliant, the version of PEAR packaged with Horde contains a DB module that is NOT PHP 5 compliant, which causes miscellaneous and sundry issues with Horde. Here is a quick fix:

pear upgrade DB
cp -a /usr/share/pear/DB.php /usr/share/pear/DB/ /usr/share/psa-horde/pear/

Unfortunately, due to openbasedir restrictions, a straight "cp" is the cleanest solution. Once this is complete, Horde should function properly (still not sure if this resolves everything).

Sometimes it is necessary to relax the open basedir restrictions for a particular domain. To do this, you'll need to create a vhost.conf for that domain, or edit the existing one. For this example, we will use 'test.com' as the domain.

vi /var/www/vhosts/test.com/conf/vhost.conf

<Directory /var/www/vhosts/test.com/httpdocs>
    php_admin_flag engine on
    php_admin_value open_basedir [insert appropriate restrictions here, or 'none' to disable]
</Directory>

/usr/local/psa/admin/bin/websrvmng -av

All you need to do is paste the following into a file in a web-content directory (typically phpinfo.php or info.php):

<?php
phpinfo();
?>