I cannot claim the credit for this, that rests entirely with 'Bosh' who found the solution over a year ago.

November 2008. And people are still wandering about looking for solutions. like me.

I LOVE this forum.

So here it is.
1. follow the steps. So easy it's ridiculous.

Use phpinfo to find out if your version on your server is V.4 or V.5
If it's 5 - then download the phpmailer 5/6 version
If its 4 - then download the phpmailer 4 version

The one included in the Zen distribution is ancient in any case.

In short. The update to phpmailer for php is on the code base at this address: phpmailer.codeworxtech.com/index.php

Download the phpmailer 5/6 and unpack into a temp directory.

Follow the steps shown in the message extract below.

Make sure you use ASCII to ftp files.

Took me about 5 minutes, and jobs done.
...... and .... be careful if overwriting a live system.

All credit to "Bosh" - thanks my friend you saved me HOURS.

OK peeps,

I''ll tell you I've found out so far and what I've done about it. I'm not saying
the issue has gone away yet but now Nochex receives whats being sent, whatever
that is because is complains with a wrong "email address" or "Merchant ID". But
that should be fixable.

Fistly, I examined the code /include/classes/class.phpmailer.php. The first thing
that struck me was - it's old and it really shouldn't be sitting ontop of PHP 5.x.x.
Your host is using PHP 5.x.x aren't they, perhaps you should move.

Anyway I went here; phpmailer.codeworxtech.com/index.php
and downloaded PHPMailer for PHP5/6 and unzipped/tar'd them into a tempory directory.

Secondly, after doing a few eyeball checks (I'm not that cavalier), I did
this ...
1. replaced - /include/classes/class.phpmailer.php
2. replaced - /include/classes/class.smtp.php
3. added - /include/classes/class.pop3.php

also in /include/classes/support/ I replaced all the language files provided
in the download. Although I only needed the English one, I like to be consistant.

Now, as I said, more testing is required on the PHP side before I'm satisfied and
it's unlikely I'll be using SMPT so I won't be testing that. Perhaps someone
else who requires SMPT would undertake that and provide some feedback for others
who might want to use it

As for myself, when I'm satisfied with my testing I'll tell you here whether
its broken anywhere or that its all OK.