In your specification
, I did not find the possibility of using group addresses. It seems that using group addresses allows you to make functionality similar to channels and groups in other instant messengers like Telegram or Hipchat. I understand that your decision is due to independence from the mail provider. But in the corporate segment, creating a group address, creating a list of recipients and appointing its administrator is not a problem. Many have mail hosting where creating group addresses is not a problem too.
Do you plan to support group addresses?