I use Postfix for SMTP. Inbound emails arrive directly at my server without any intermediary. Outbound emails use Postfix sender_dependent_default_transport_map

I use Postfix for SMTP. Inbound emails arrive directly at my server without any intermediary. Outbound emails use Postfix sender_dependent_default_transport_maps, which routes outbound emails via mailgun. I use this method because I host multiple domains and it lets me use domain-specific credentials with the SMTP relay. Outbound routing could be done using the same credentials for all domains but that causes some unnecessary pollution in message envelopes.