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On Exchange/O365,can a single user subscribe for push notifications (using EWS) from a multiple users ? I know this is possible using impersonation but would like to know if we can achieve this using delegation. If yes , what would the request look like ?

Side question: Are there any limits to number of accounts that can be delegated to a single user ?

Thanks

Twaha Mehmood
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1 Answers1

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You can but they need to separate subscriptions eg you can't create a single Push subscription that subscribes to folders in different Mailboxes (eg the Inbox in Mailbox 1 and Mailbox 2). You can create a separate Push subscription against any folder in any Mailbox you have access to (eg Subscription 1 subscribes to the Inbox in Mailbox 1 and subscription 2 subscribes to the Inbox in Mailbox 2), and you can create a subscription that subscribes to multiple folders within one mailbox.

Side question: Are there any limits to number of accounts that can be delegated to a single user ?

No but there are throttling restrictions that control how many Mailbox you can connect to concurrently as well as how many you can create subscriptions against https://blogs.msdn.microsoft.com/exchangedev/2011/06/23/exchange-online-throttling-and-limits-faq/ .

Glen Scales
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  • Thanks! The link above mentions "The server starts to return errors when the number of open connections reaches approximately 20 for a user. " So does this mean that the max number of subscriptions that can be done, the way you have suggested above, is 20 ? I hope this limit is not there for impersonation. – Twaha Mehmood Apr 03 '17 at 10:21
  • https://msdn.microsoft.com/en-us/library/office/jj945066(v=exchg.150).aspx "Because the EWSMaxSubscriptions throttling budget is charged against the account being impersonated, there is no limit on the number of mailboxes a service account can subscribe to and receive streaming notifications for, as long as impersonation is being used. For the account being impersonated, you can't have more than n concurrent requests per target mailbox, where n is the EWSMaxSubscriptions value. If you were not using impersonation, the same service account could not have more than n concurrent requests total" – Glen Scales Apr 04 '17 at 04:18
  • In my case I have an account 'A' to which >20 users (B,C,D ...) have delegated their access. Now subscribe for push notification for all the (> 20) users using account A. So as per your previous answer this wont work .. right ? – Twaha Mehmood Apr 04 '17 at 07:51
  • If you use impersonation you won't have a problem, you may want to read https://blogs.msdn.microsoft.com/exchangedev/2012/04/03/exchange-online-ewsmaxsubscriptions-throttling-budget-calculation-has-been-updated/ why you may not hit the subscription limits due to this you may find you breach other throttling limits. If you want to avoid problems use impersonation. – Glen Scales Apr 05 '17 at 01:37