I've now done some testing with the cooperation of Lorraine.
It did not work out like anything I had expected at all.

She tried blocked me -> was taken to an upgrade membership page.
She unblocked another person -> Immediate effect on stats.
I blocked her -> No effect on stats (I refreshed several times).

I'll leave her blocked until tomorrow to see if registration is slow.

While I wait for someone else to test this with it appears that
I was blocked by an upgraded member, although it seems
strange that blocking is for upgraded members only.

Now I have done some more testing with Andrew.
Actually it seems we broke something.. ;)

Finally understood that the blocking we see in our stats
comes from people clicking the blockbutton in our PM's to them.
Not from the blockbutton you see on each friend in your friendslist.

When you try to send a PM to someone that's blocking you,
then you get the notification that you're being blocked.

Just clicking on send message isn't enough,
you have to actually try to send one.

Blocking forum announcements/invitations is for upgraded members only.

Roger

I have never blocked anyone as I value all the Adland members as my friend.

I however have been blocked by one person and I think I know who it is

but have never really found out.

Leslie

Hi Leslie,

If you think you know who the person is you can check
the stats and see if the person is blocking 1 or more of their friends.

If the person is blocking 1 friend or more you could send a
testmessage or similar and if it goes through you guessed wrong.

If it gets stopped you were right.. ;)

To check all your friends, which I do right now, would take you
4 times the time it takes me and it's really not that important..

Shouldn't be that important to me either, but I got stuck.. ;)

This will not necessarily work.

I just finished visiting every single friend I have.
I checked the stats of every friend and sent a msg to
every friend that was blocking 1 or more friends.

None of the messages failed.

I have told support that I would like this error (as I see it) fixed.