I have submitted this question to support, but I thought I would ask here in case someone knows. I manage a Dreamhost discussion list that uses the subdomain lists.wedgeblade.net which Dreamhost created when I created the listserv. I have wedgeblade.net registered and can manage the domain at Dreamhost.
I have a list user with an Apple email that can receive list mail but cannot post. Folks with other email providers have no problem. Apple support says that the problem is that the subdomain lists.wedgeblade.net has no MX record. They are correct about the missing MX record, but the top-level domain wedgeblade.net does have the correct Dreamhost MX record. For some reason other email providers use the top-level mx record but Apple does not.
I don’t know if Apple is wrong for not using the top-level domain wedgeblade.net MX record or if Dreamhost should have created a lists.wedgeblade.net MX record. I have noticed that other mailman hosts do have subdomain MX records. For example, the fine xmission.com folks have MX records for both their top level domain and the mailman.xmission.com subdomain where they host their discussion lists.
I don’t see a way to add the MX record myself for the lists.wedgeblade.net subdomain using the Dreamhost control panel. In any case, if the MX record is needed, Dreamhost should create it when the discussion list is created.
I would appreciate any wisdom on this.