On the list of e-mail addresses for sending invitations, the following status appears next to the e-mail address: "The recipient has blocked the possibility of receiving invitations from the Startquestion's system.". What does it actually mean?

This status means that the person with the given e-mail has opted out of receiving invitations to complete the survey. This could have happened during the current invitation mailing or previous sendings. This applies to sendings of all the users of the Startquestion.com website. More information on this topic is available on our blog.