We are seeing regular patterns during donations that where certain hosts/domains complain about our connection speed and then send us a 4XX code to defer/retry the email. Common patterns in the logs are: too many connections, slow down, later time

One that commonly shows up with these patterns is orange.fr.

We should set up a slow roll transport for these particular hosts/domains. We can reduce the conection concurrency below the current limit to help slow our roll and hopefully ensure a more timely delivery of mail overall to their users