Right now, we are using Zammad for internal requests only. Those are basically requests from external customers (who must not be notified about it) but all tickets are solely created and handled by our agents.
That is why the agents are supposed to always set their own user as customer when creating new tickets. But there are always some employees who nevertheless try to enter the external customer.
As a result our Zammad instance clutters up and will create error messages when it tries to send mails to customers without mail addresses.
Channel: Email::Account out Can't use Channel::Driver::Smtp: #<Net::SMTPSyntaxError: 501 5.5.4 Invalid Address
(By the way, how do you flush the mail queue or clear this error state?)
Even in the future, when we start using Zammad with tickets directly created by external customers, adding new customer users to the system should be always restricted to our admins or customized mini-admins.