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Exchange Calendar Integration

  • March 26, 2026
  • 3 replies
  • 3 views
M

Hi there, 

 

We are trialing calendly for our organization and are trying to get it to connect to our on prem Exchange 2019 server.

 

I have checked and we have correctly whitelisted all traffic from the calendly IP list provided at https://ip-whitelist.calendly.com/ ; We pass all connection tests on the microsoft connectivity analyser; but when I try to connect with my exchange email and password, whether or not I fill in the Server URL and Domain and Username, it always fails. We are not seeing any connection attempts on our edge proxies.

Thanks!

3 replies

David
Community Manager
  • David
  • Community Manager
  • March 26, 2026

Hi ​@Mav14188 - Thanks for reaching out.

Exchange connections can be difficult, just to make sure, I’ve added all of our requirements below:

  • Calendly supports Exchange versions 2013, 2016, and 2019.
  • Your Exchange account must utilize an EWS connection. ActiveSync connections are not currently supported.
  • If you are using Exchange via Amazon WorkMail, this endpoint acts on a version of Exchange that is not supported at this time.
  • Exchange IMAP/POP connections are currently unsupported.
  • If your Exchange calendar connection has a 2FA/MFA set up enabled, you will need to utilize our Microsoft Outlook Plug-In (for Windows users) instead.

If everything matches, I’d actually recommend reaching out to our support team so they can dive a bit deeper on what might be going on. They’ll be able to start a screenshare with you can take a look from there.

I’ll leave this thread open in case anyone has any tips!

M
  • Mav14188
  • Author
  • Community Member
  • March 26, 2026

Yup, we meet all of those requirements. It seems to be an issue with authentication. Does Calendly support basic authentication? As it keeps trying to negotiate NTLM.

2026-03-26T16:28:54.940Z,e4303619-4ed1-47da-a1b0-fc5e5611bf2e,15,2,1748,10,,Ews,REDACTED,/Ews/Exchange.asmx,,NTLM,false,,,,Calendly, [removed by moderator] ,DB-EXCHANGE,401,,,POST,,,,,,,,,0,,,,,,,,,,,,,,,504,,,,,,,,,,,,,,504,,504,504,,,,BeginRequest=2026-03-26T16:28:54.436Z;CorrelationID=<empty>;SharedCacheGuard=0;AnonymousRequestFilterModule=AnonymousRequestDisallowed;EndRequest=2026-03-26T16:28:54.940Z;S:ServiceLatencyMetadata.AuthModuleLatency=485;I32:ATE.C[db-ad.internal.dobusiness.com]=5;F:ATE.AL[REDACTED]=4.2;I32:VCGS.C[DB-EXCHANGE]=3;Dbl:VCGS.T[DB-EXCHANGE]=0;I32:ADS.C[REDACTED]=3;F:ADS.AL[db-ad]=1.407367;I32:ADR.C[db-ad]=2;F:ADR.AL[db-ad]=1.7344,,,,,,

David
Community Manager
  • David
  • Community Manager
  • March 26, 2026

Hm okay, thanks for sending this over. I will admit this one is a little over my head, however,  I would definitely suggest chatting in with the support team then - They should be able to get a more detailed error code of what is going on here, and assist you in getting it connected.

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