ok, I moved the thread to Fabrik3.1+ forum.
So you are running Fabrik3.2 on Joomla2.5 (this is possible but not so common)
With Fabrik3.2 (ie Fabrik3.3.1 meanwhile) on Joomla3 I can't replicate your issue, no difference between co.uk and other email addresses.
If you are going to update to Joomla3 anyway I would suggest to see if there are still theses issues.
You don't have to do this Fabrik migration stuff because you are already running Fabrik3.2
But keep in mind that with Joomla3 Fabrik needs a Joomla bootstrap template (BS2, compatible with e.g. Protostar coming with Joomla) and you have to switch your Fabrik list/form/details templates to the new Fabrik bootstrap ones.