Mark, 

Thanks for all your hard work on this.  It’s a thankless task at times.

Re “I don't know how to prevent that behaviour”: you might need to publish some administrator guidelines.  One thing that is necessary is house-keeping.  Administrators need to do a minimum to keep their data up to date, review the meber list at regular intervals specially those that run open groups.

I don’t allow anyone to join unless I have some indication they are a genuine person.  If we get an anonymous application and can’t trace the sender, we ask them to provide a minimum of info.  You’d be surprised how many of those request remain unanswered.  So, it’s worth checking.

When I first joined the premium service, the one facility I wanted was “direct join”.  All recipients can reject the invitation if they want so I don’t consider it being intrusive.

But I’d request improvement to the member database and the ability to sort, the splitting up of display name into “First “and “Last Name”.  It would be really good if w could set up a weekly/monthly report on bouncing or problematic addresses.

I know you can get these reports by downloading various lists but the amount of work afterwards to make them user friendly is prohibitive.

How difficult would  async facility between the system address database and the database section of the site be?  Then investigations and filtering would be possible from within io.groups.

But the basic requirement is for administrator to be firm with their members, if they don’t want to identify themselves, what is it they are wanting to hide.  We only ask for first name, last name, email and town/city and country of residence.  Not exactly the Spanish inquisition.

Hope this helps you look at behavioural change.

Cheers

John