Though I use Captcha and reCaptcha, I have a lot of dummy users and Contacts which I can identify by the fact that their sort_name = display_name = email (or sort_name contains an "@").
How can I delete those Users and Contacts ?
My original idea was to create a Dynamic Group of those, then delete them after exporting their list to excel to delete the relevant Users. But, how to create such a Dynamic Group (based on what search criteria ?) ?
An alternative would be to create a View (filtered on "sort_name contains '@'"), then use VBO to add them to a Group : I tried, but could not succeed).
I tried using the Search Builder, but it is broken : I have openned a new post for that : Search Builder is broken (Civi 5.4.0 / Drupal 7.59)