15 December 2017 – there seems to be a problem with the Invitations feature, where invitations to email addresses outside the university (i.e. not email@example.com) are not being sent. The technical team are investigating.
In the meantime, you can use Outlook to email your invitation list (use the BCC feature so they don’t all see a list of every recipient) and include the standard link to the survey (e.g. https://isurvey.soton.ac.uk/16571) . The use of invitations does not prevent access and completion by anyone who knows that link. Of course you won’t be able to track completion – sorry – but you will be able to run your survey.
You can email the same people a week or so later to remind them, including an apology to anyone who has already answered.