This is related to Magento's translation function. I wouldn't worry too much about it. Also read this question.
The email adress is fake. It is only displayed in a warning message if and when customers enter an invalid email address. Its purpose is to show them an example of what a valid email address would look like. Also it is not your own email address, so why worry about spam?
Like all other people who answered this question recommend: Just leave this as it is...
But if you really, really, really want to change or remove this then look at the following files:
app/code/core/Mage/Core/etc/jstranslator.xml
app/locale/yourlanguage_YOURLANGUAGE/Mage_Core.csv
/js/prototype/validation.js
Warning: Like @Sander says, removing or editing this might be very tricky. So only
touch those files if you are exactly aware of what you are doing.