Setting up a new domain will result in the following error trying to send the initial verification email:
Feb 13 22:47:20 app postfix/smtp[205]: 7BAA8170C8F: to=mailbox@example.com, relay=app.mydomain.com[255.255.255.255]:25, delay=1.5, delays=0.08/0.04/0.64/0.79, dsn=5.7.1, status=bounced (host app.mydomain.com[255.255.255.255] said: 554 5.7.1 Sender address sl.lmzcyibqfqqdemjwg4yten25.wj7jbbbajmc2a@mydomain.com blocked using ZRD - domain too young (in reply to RCPT TO command))
Setting up a new domain will result in the following error trying to send the initial verification email: