The forum for the Inter-Experimental Machine-Learning (IML) WG is a cern e-group, i.e. the mailinglist lhc-machinelearning-wg@NOSPAMcern.ch. It is open for self-subscription for everybody and does not require approval by the administrators. All members of the e-group can post messages. If you do not have a CERN computing account, you can create a lightweight account here.
The e-group is archived here.