Technical Exchange bLog

 If you got this error checking the mail flow for a distribution group, it means the distribution group is closed and only internal senders can send e-mail to this group. When outside user sends e-mail to this group you get  Reason: [{LED=250 2.1.5 RESOLVER.GRP.Expanded; distribution list expanded};{MSG=};{FQDN=};{IP=};{LRT=}] Set Delivery for this group to internal and external users and your problem will be solved. 

An Exchange Online license was applied to the user before the Exchange GUID got synchronized from on-premises Active Directory. For synchronized accounts, having the Exchange GUID synchronized from on-premises is used to tell Exchange Online that the mailbox hasn’t been migrated yet, and is what allows customers to pre-license accounts prior to migration.  From:  My user has a mailbox both on-premises and in Exchange Online. So, in my case many times we get into situation where license is applied before Exchange GUID is synchronized to O365. I am using this script to check whether user has two mailboxes. Script closes Exchange session BEFORE it opens connection to Exchange Online as both use same commands. You can use Get-Mailbox both on-prem and Online, therefore it is crucial to close connection before you open other. # DISCLAIMER: # This code is provided "as is" without warranty of any kind, either express or implied, including but not limited to the implied warranties of

 I was trying to log in with Smart card (Yubico in my case) but server could not log me in and returned the error: An untrusted certification authority was detected while processing the domain controller certificate used for authentication additional information be available in the system event log. Please contact your administrator. Checked the certificate store and required certificates were in the store. In my case Root CA and Intermediate CA certificates. When I ran the command  certutil -viewstore -enterprise NTAuth in the elevated PowerShell window I got no certificates. Therefore, I exported the intermediate certificate from the store (certmgr.msc), put it in the C:\TEMP path and ran: certutil -enterprise -addstore ntauth "C:\TEMP\intermediate.cer" After that I was able to sign in with smart card. Whay certificate was not propagated through domain is still a mystery :) 

 If you are using Microsoft's Azure Backup server to backup your Exchange you might want to use notifications if anything goes wrong with it. In the Options window when you enter credentials for the sending account it keeps failing to send test E-mail saying wrong username and password (error 2013).  The problem is that this account needs to have local admin rights on the Azure backup machine.  Yeah, don't ask why.

We had a problem where M365 users could not retreive Free/Busy information from on-premise Exchange server. Hybrid setup was run and everything was working fine except this. After research I found out that TargetSharingEpr is the way to look at. There are many sites out there that are pointing to the same setting but only Set-OrganizationRelationship is used to change the value. The problem is, this value is available for two commands: Set-IntraOrganizationConnector Set-OrganizationRelationship While we changed the value in  Set-OrganizationRelationship it didn't work until we changed the value in  Set-IntraOrganizationConnector too. By default it should work with just  TargetAutodiscoverEpr but for us it didn't. Finally we ran this command on Intra Organization Connector which is used from Cloud to On-prem:  Set-IntraOrganizationConnector -TargetSharingEpr   https://mail.domain.com/ews/exchange.asmx And it worked.

If you have a problem with Microsoft Teams not showing Calendar for users that have on-prem mailbox then you missed some of the steps in making a hybrid. To be honest, sometimes it is not very easy and clear what exactly you have to do. In my setup I am running Exchange 2019 on Windows 2019 server. 1 . First step is to run Microsoft Office Hybrid Configuration Wizard This step is necessary even if you ran AD Connect and selected Exchange Hybrid. Go through the Wizard and when you finish, it will tell you you need to configure OATH manually as it is not part of the Wizard (in year 2020) 2. Follow all the steps on https://docs.microsoft.com/en-us/exchange/configure-oauth-authentication-between-exchange-and-exchange-online-organizations-exchange-2013-help For me step 8. was not necessary as I am running Exchange 2019. After successful implementation of OATH connection Calendar will be immediately available to Teams users. Test connection with: ON-PREM Ex