This will be stored as the 'login_entry' for your participant.
This might be a better option for you.
When you're setting up a survey, you shouldn't combine the url
parameter with a 'Participant Identification' type, because the url
parameter will over-ride the standard identifier. Just choose
'Anonymous' when setting that up on the access tab. If you also
need to collect an email address or some other identifier, you will
want to collect that using a pre-survey questionnaire question,
rather than the 'Email address' participant identifier.
If this is all getting a bit confusing, just let me know and
I'll give you a call to discuss your options.
Legend! We launched a new feature on Monday which allows you to
filter the automated results stuff (dendrograms etc) based on
answers to pre and/or post survey questions. It's not complete yet
but we have another release coming next Monday which will bring it
up to 99% completeness.