Why am I receiving the 401 HTTP ERROR when calling GetSharedMailbox in Redemption?

Question

I am using Redemption to access the shared mailboxes. The Logon method that I am using is Session.LogonExchangeMailbox.

It seems to be working fine as long as I do not try to access the shared mailbox. Once I am trying to access shared mailbox, there is the following error:

Redemption.RDOStores: Could not find the store DN Could not retrieve autodiscover XML: GetAutodiscoverForEmailAddress: There are no autodiscover servers in the AD for this address Error in WinHttpSendRequest(bcg.com/autodiscover/autodiscover.xml): ERROR_WINHTTP_TIMEOUT Error in WinHttpSendRequest(bcgcloud.mail.onmicrosoft.com/autodiscover/autodiscover.xml): ERROR_WINHTTP_NAME_NOT_RESOLVED Error in WinHttpSendRequest(autodiscover.bcgcloud.mail.onmicrosoft.com/autodiscover/autodiscover.xml): ERROR_WINHTTP_CANNOT_CONNECT HTTP error 401 from https://autodiscover-s.outlook.com/autodiscover/autodiscover.xml

What I tried:

1. adding credentials with RDO.Credentials.add - does not change anything
2. LogonHostedExchangeMailbox - does not work in my case at all - I guess because of Basic Auth being disabled (and I cannot get OAuth token for modern auth)

Checking the server version with Session.ExchangeMailboxServerVersion has shown that we have 15.20.4995.8 - looks like we have Exchange 2019 where RPC-Over-HTTP is not supported anymore. Then the question would be how could Session.LogonExchangeMailbox work at all even with DefaultFolder? Why does it error out only in case, if I am trying to access sharedmailbox?

Thanks.

Answer 1

It seems your choice is only the LogonHostedExchangeMailbox method. Here is what the author of Redemption wrote:

LogonExchangeMailbox creates a temporary profile that uses plain RPC connection. Exchange 2013 and 2016 do not support RPC connections anymore, only RPC-over-HTTP or MAPI-over-HTTP. You need to use LogonHostedExchangeMailbox for that.

See What is a RDOSession.LogonExchangeMailbox server name for outlook.com? for more information.

In case of Exchange profiles/accounts I'd suggest using EWS instead. See Explore the EWS Managed API, EWS, and web services in Exchange for more information. Also you may consider using the Graph API.