A customer has two subscriptions - #1000101 and #1000102, both subscriptions have Qmail hosting and Open-Xchange services.
Customer logged into their control panel, created domain customer.com and added Qmail hosting to the domain from the subscription #1000102.
Then customer switched to the subscription #1000101 and tried to add new mailbox on the domain customer.com (which has Qmail hosting from the subscription #1000102). During the mailbox creating customer selected desired type of Open-Xchange service to be enabled for the mailbox.
On the last step customer clicked the button 'Finish' and the following error appeared:
Mailname creation result:
Mailname creation failed: Service 'E-mail' is required by service 'Open-Xchange'.
The reason of problem is that active (currently selected) subscription in customer CP is #1000101 and POA is trying to use Open-Xchange resource from this active subscription. However, Qmail service for the domain was enabled using resource from the subscription #1000102.
So, POA cannot provision Qmail and Open-Xchange services to the same domain from different subscriptions.
Customer either need to remove Qmail hosting from the domain customer.com and re-add it using Qmail resource from the subscription #1000101 (of course, it may be done only if there are no mailboxes created in the domain yet) or they need to switch active subscription to #1000102 and add mailboxes using both resources Qmail and Open-Xchange from the same subscription.