As usual… found it:
• cleartk-issues - this list receives emails generated by the issue tracker. Every time a comment added or a change is applied to an issue, an email is generated and sent to this list. This is probably the best way of keeping track of development efforts that are going on in the ClearTK project. It is generally inappropriate to post directly to this list. Instead you are encouraged to add your comments directly to an issue.
How about adding those to the "groups" section in the project sidebar along with the users and developers list ;)
-- Richard