The abuse check now lives externally. As a generic mechanism vanmeeuwen suggested that we may be able to install an app/Handler/Abuse.php just like we do for app/Handler/Mailbox.php, and that this might provide a suitable generic hook to run an abuse-check background job.

I have not validated that idea.

I suppose Handler::created could be used to spawn a job, not sure if it is a good solution or not.

CreateJob is already async, so I don't really see a reason to invoke another job. At least the point is to not create the mailbox/ldap record if the abuse check didn't finish yet.