We are a company who is developing a software for managing our email service dynamically by code in .NET.
What we try is, from an email account we create an streaming service.This account is allowed to access to all mailbox accounts in the company, so all emails received in each mailbox go through this account. Here it's an example about one streaming subscription to one mailbox.
FolderId folder1 = new FolderId(WellKnownFolderName.Inbox, new Mailbox("prueba@XXX.YYY"));
StreamingSubscription subscription = _ExchangeService.SubscribeToStreamingNotifications(new FolderId[] {folder1}, new EventType[] { EventType.NewMail, EventType.Moved });
For doing that, we've focus on Exchange 2010 and everything goes well because de EWSMaxSubscriptions is suppossed to be 5000, and we don't have more than 100 mailboxes. Recently, we've tought about supporting to Exchange Online (Office 365, Small Company Plan), and we've tried the same but we can't subscribe to more than 20 mailboxes by streaming, this exception is thown: You have exceeded the available subscriptions for your account. Remove unnecessary subscriptions and try your request again.
How can we increase in Exchange Online this limit?
Why is this number too low in Exchange Online?
Is it neccessary to buy a bigger plan for Office 365 to increase the number of subscription by streaming?
Thank you in advance