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Exchange Online EWSMaxSubscriptions throttling budget calculation seems to have changed RRS feed

  • Question

  • We’re monitoring our room’s client calendar to inject the bookings in our software solution. Each company provides us one service account used to interact with EWS of Office 365

    In order to monitor our calendar’s clients mailboxes we use an EWS method : PushSubscriptionRequest

    Since last week we’re facing a major issue while sending the PushSubscriptionRequest call. The response sent back is :

    SubscribeResponseMessageType){
             _ResponseClass = "Error"
             MessageText = "You have exceeded the available subscriptions for your account.  Remove unnecessary subscriptions and try your request again."
             ResponseCode = "ErrorExceededSubscriptionCount"
             DescriptiveLinkKey = 0
             MessageXml =
                (MessageXml){
                   Value[] =
                      (Value){
                         value = "20"
                         _Name = "PolicyLimit"
                      },
                }
          }
    

    It’s happening when the service account tries to subscribe to more than 20 rooms mailboxes . All of our clients with more than 20 rooms are impacted (the biggest ones).

    This subscription process was working with absolutely no error since 2 years, it seems to have change recently ! (near 26th august)

    We’re aware there are EWS throttling policies but as the MSDN Article explains the most important thing to understand is the calculation to achieve this limit:
    https://blogs.msdn.microsoft.com/exchangedev/2012/04/03/exchange-online-ewsmaxsubscriptions-throttling-budget-calculation-has-been-updated/

    « Starting with service mailbox versions 14.16.0135 and 14.15.0057.000, this limit has changed. Now, the charges are counted against the target mailbox rather than the calling account. This way, a service account can create subscriptions against many more than 20 mailboxes. One benefit of this change is that you can now design a service application that targets Exchange Online and Exchange on-premises using a similar code base for subscription management. A single service account can now service up to 5000 subscriptions. »

    Why can't we subscribe to more than 20 subscriptions whereas the article indicates 5000 ?

    Above all why the budget calculation has changed? Are we alone to experience this update?

    Monday, September 4, 2017 3:38 PM