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I am using outlook api v2.0 rest api to perform crud operations against calendars and events and have started hitting a rate limit issue.

This one for example is hitting the calendarview endpoint:

GET https://outlook.office.com/api/v2.0/me/calendars/{CALENDAR_ID}/calendarview

RESPONSE HEADERS

  • Rate-Limit-Limit=10000
  • Rate-Limit-Remaining=9982
  • Rate-Limit-Reset=2019-10-23T15:27:11.409Z
  • Retry-After=1
  • RateLimit-Exceeded=MailboxConcurrency
  • RateLimit-Scope=Mailbox
  • Transfer-Encoding=chunked
  • X-Proxy-BackendServerStatus=429
  • X-Powered-By=ASP.NET
  • X-RUM-Validated=1

RESPONSE BODY

{
    "error": {
        "code": "ApplicationThrottled",
        "message": "Application is over its MailboxConcurrency limit."
    }
}

At first I thought it was the 10.000 requests per 10 minutes period but it seems I am hitting a different one.

Antonio Acevedo
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1 Answers1

3

The error is showing that you've hit the mailboxconcurency limit. There is a limit of 4 concurrent requests as per the documentation.

Is there any reason you are using this API rather than Microsoft Graph also?

https://learn.microsoft.com/en-us/graph/throttling#outlook-service-limits

Jeremy Thake MSFT
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  • Documentation says 4 concurrent request are for beta endpoints but there is no indication the one I am assuming is beta anywhere? – Antonio Acevedo Oct 26 '19 at 08:09
  • According to Outlook docs for that endpoint there is: - A beta version: `GET https://outlook.office.com/api/beta/me/calendarview` - A v2.0 version: `GET https://outlook.office.com/api/v2.0/me/calendarview` Given so I was expecting the concurrent requests limit would only apply to the former. Am I wrong? I am really keen on moving to the new Graph API but the docs say Graph V1 matches Outlook v2 (https://learn.microsoft.com/en-us/outlook/rest/compare-graph#api-versions) so I was hoping I can get the concurrency issue fixed before migrating. – Antonio Acevedo Oct 26 '19 at 08:20
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    The concurrent limit is for both v2.0 of outlook.office.com AND graph.microsoft.com . I have just confirmed this with the architect. – Jeremy Thake MSFT Oct 29 '19 at 03:35