"Hi Jingle,
Hope you're well.
We wanted to drop you a line about your recent posts, as we have had a lot of complaints from other posters about the tone of your posts.
As you know, we have absolutely no problem with you (or any other gransnetter) expressing strong opinions, we are a little concerned with the way you have been expressing them lately.
We would like to remind you that our raison d'être is to make grandparents' lives easier by pooling and sharing advice and support. We ask members to respect each other's opinions even if they don't agree with them.
We'd be grateful if you'd bear this in mind in your future posts, otherwise we may have to take further action.
Trust you understand,
GNHQ"
It started off nice. 
It's just the "further action" that is worrying. [chews nails]