I have a reseller plan in isp hosting. I submit a ticket about that and today said this:
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We have contacted Parallels long time ago. The main issue is that Plesk process domain related tasks in a queue with one active task at a time. If 10 users are trying to add domains, only one will be active and the rest will have to wait their order.
Another issue is that Parallels Plesk API still uses commands from IIS 6 mode.
All this has been communicated with them, but unfortunately they haven't upgraded their software and there is nothing we can do on our end.
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