Thanks for that module :)
Just a note, I don't think the second url is needed anymore (region_url2)
On my EC2 (ubuntu 18.04), I removed it from /etc/postfix/sasl_passwd
then reloaded it via
postmap /etc/postfix/sasl_passwd systemctl reload postfix #probably not needed but just in case
authentication is still working, test email was sent and received.
also, not sure the url2 exist anymore
nslookup ses-smtp-prod-335357831.us-east-1.elb.amazonaws.com Server: 127.0.0.53 Address: 127.0.0.53#53 ** server can't find ses-smtp-prod-335357831.us-east-1.elb.amazonaws.com: NXDOMAIN