the picker allows you to pick "Access Control List only" groups & the Terminations group.  When you select groups like that in the regular Notes client, you get pop-up error messages saying "the selected entry does not have a valid address". 

It would be nice if the picker window showed the group type icons like it does in the Notes client but it doesn't.

What would be the best approach to get around this?  Validate entries after the fact to ensure they are valid groups for emailing?  Or, use a custom data provider to only display valid groups & people for picking in the first place?  What have other people done?