All AAS members are invited to participate in SGMA. To receive updates about SGMA activities, please join the SGMA Members mailing list by going to https://lists.aas.org/ and entering your name and email. Select "sgmamembers (SGMA Members)" from the drop down menu, and click the green Subscribe button. You will receive an email with a link to confirm your subscription. You must follow the link and confirm your subscription in order to join the mailing list. If you encounter any issues, contact SGMA at firstname.lastname@example.org.
The LGBTIQA astronomy community in the US has a general email list, GLBTQastro which everyone is welcome to join.