Merge branch '6669-mail_domain_add-with-api-fires-mail_mail_domain_edit-with-event-where-a-new-domain-case-check' into 'develop'

Resolve "mail_domain_add() with api - fires mail_mail_domain_edit with event where a "new domain" case check is missing on user/spamlist update"

Closes #6669

See merge request ispconfig/ispconfig3!1867