Cross domain tracking not recording goals from email campaigns

[Jon Sharkey]

Hi, I've recently set up cross domain tracking to connect registrations from www.excursions2016.com which take place on a third party website with the same tracking code. The code implemented is as follows:

Main website:

<script>
	(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
	(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
	m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
	})(window,document,'script','//www.google-analytics.com/analytics.js','ga');
	ga('create', 'UA-5019536-25', 'auto', {'allowLinker': true});
	ga('require', 'linker');
	ga('linker:autoLink', ['onlineregistration.co.uk'] );
	ga('require', 'displayfeatures');
	ga('require', 'linkid', 'linkid.js');
	ga('send', 'pageview');
	</script>

Registration website (http://www.onlineregistration.co.uk/shows/excursions/16/regexcur.php?new=1):

<script>
	(function(i,s,o,g,r,a,m){
	i['GoogleAnalyticsObject']=r;
	i[r]=i[r]||function(){
	(i[r].q=i[r].q||[]).push(arguments)
	},i[r].l=1*new Date();
	a=s.createElement(o),m=s.getElementsByTagName(o)[0];
	a.async=1;
	a.src=g;
	m.parentNode.insertBefore(a,m)
	})(window,document,'script','//www.google-analytics.com/analytics.js','ga');
	ga('create', 'UA-5019536-25', 'auto', {'allowLinker': true});
	ga('require', 'linker');
	ga('linker:autoLink', ['excursions2016.com'] );
	ga('require', 'displayfeatures');
	ga('require', 'linkid', 'linkid.js');
	ga('send', 'pageview');
	</script>

Upon testing and judging by reports in Analytics, this appears to be working fine for visits by organic search and referrals, but not through email campaigns where I am adding a UTM string to the links such as.... 

http://www.excursions2016.com/getting-here/transfer-coaches.html?utm_source=GroupTravelWorldTransferCoach&utm_medium=email&utm_campaign=Excursions2016

Is there any particular reason why it would work for visits of some acquisition types, but not campaign links with UTM strings? Thanks.