as we are a new ESP our own IP gets marked as SPAM on Microsoft eMail-services(O365, Outlook.com, Hotmail).
While we are gaining reputation we have a temporary solution to send mails through old ESP which domain were migrated into ours. That works and we have tested it.
My question is, when I do Gateway on SmarterMails configurations the gateway can be only Enabled or Disabled. When I disable that Gateway all the mail go through our own ip, but when I enable it all the mails go through that gateway. How can I configure the gateways so that when on the domain level I set Outgoing Gateway it uses that gateway? And otherwise when Domain has no Outgoing Gateway set, it uses the default as in this case our own ip?
Do I need to create a gateway of our own server and enable it so that both gateways are enabled. How does it then determine which to use?