Exchange topics

Hybrid Exchange 2019 move to M365

Dzung Vu — Wed, 29 Apr 2026 01:52:11 GMT

Dear All,

I am asked to move/ migrate the existing Hybrid Exchange to M365.

All mailboxes are located in M365.

MX Record is pointing to the third-party spam filtering company which we are not too sure either stay with them or not.

My next concern is the Send and Receive connectors.

has any one of you done similar task like this? any help or document/ link would be much appreciated.

Regards

Exchange 2016 Decommission

JonnyShaw1 — Mon, 27 Apr 2026 22:16:57 GMT

Hi all,

I am trying to decom my 2016 environment and cannot disable (Disable-Mailbox) the final 16 mailboxes (out of thousands). Am getting the error

Active directory response: 00002098: SecErr: DSID-03150A45, problem 4003 (INSUFF_ACCESS_RIGHTS), data 0.

I have been troubleshooting this for HOURS now. It's not enabling inheritance on the user perms (every article suggests that). The perm exchange trusted subsystem isn't there. The users do not have any admin groups. It's nothing that I can find in the first 6 pages of googling. Sadly, of course, there is no support anymore so can't even raise a ticket.

Can't uninstall Exchange with mailboxes left :(

Any idea's are more than welcome, please.

Thank you.

Permission activesync on smartphone

AnonymousForever — Sun, 26 Apr 2026 07:54:51 GMT

Hi everyone, when you grant the permissions in question to manage company email from a smartphone, do these permissions, in addition to Remote Wipe, Password Enforcement and Device Encryption (I remember these as the main ones), somehow give the Exchange administrator access to my personal data? For example, photos, any documents saved on the SD card or on the smartphone itself?

Thanks in advanced!

Will these commands fix our phantom meetings issue?

RyanSteele-CoV — Fri, 24 Apr 2026 16:04:49 GMT

I opened a ticket with Microsoft Support for an issue we are facing where "phantom" meetings are appearing in at least two of our meeting room calendars. The subject of the meeting says "Private appointment" and the lock icon appears at the bottom, and when you click on any of them they disappear from the calendar, only to re-appear when you navigate away and come back. They appear in Classic Outlook, New Outlook and Outlook for the web.

The support rep is telling me to run these commands on the room mailbox to "reset the room mailbox availability cache":

Set-CalendarProcessing -Identity <roommailboxupn> -RemoveOldMeetingMessages $true Set-CalendarProcessing -Identity <roommailboxupn> -AutomateProcessing AutoAccept

But if I run Get-CalendarProcessing, it confirms that these are the existing settings already:

Get-CalendarProcessing -Identity <roommailboxupn> | fl RemoveOldMeetingMessages,AutomateProcessing RemoveOldMeetingMessages : True AutomateProcessing : AutoAccept

This can't possibly do anything, right? I should ask my CSAM to open a GetHelp on this case, right?

Does anyone know how to actually fix this issue?

Disabling Calendar Repair Assistant on mailboxes in Exchange Onprem 2019

PoorMens_Bravo — Fri, 24 Apr 2026 04:33:10 GMT

Hi,

We are in Exchange Hybrid setup were some mailboxes are in cloud and onprem. Recently, there were some issues with Calendar events were recipients weren't notified of any updates for the events, sometimes the updated event would have been cancelled by recipient and the recipient didn't even know that they received update and it was automatically cancelled by them....

This was a normal situation for EAs for their executive calendar events

When raised a ticket with Microsoft on this issue, Microsoft collected CDL logs and found that CRA was kicking in each time when there was an update and was reverting the updated meeting request to the previous cancellation and as we know this is not a bug, this is just how the CRA works...So, Microsoft is like CRA is a legacy feature with limited applicability and functionality in the current exchange environment and hence has asked to disable-CRA in On-prem exchange as this will not affect normal calendar usage for users.

I had disabled for 5 users and they have reverted that they are not seeing any issues post disabling CRA. so before gunning down on all mailboxes I wanted to take a second opinion on whether is it safe to disable CRA for alll mailboxes in Exchange Onprem

High Volume Email is Generally Available and Ready to Charge

TonyRedmond — Thu, 23 Apr 2026 08:31:39 GMT

On April 1, Microsoft announced the general availability for the High-Volume Email (HVE) solution together with details of the PAYG charges incurred to send email to internal recipients, which is all that HVE can do. Microsoft will enable HVE charging on June 1, 2026, Before then, you’ll need to create a billing policy and link it to a valid Azure subscription if you want to continue to use HVE.

https://office365itpros.com/2026/04/23/hve-ga-charging/

Is the Archive mailbox self-help diagnostic working for anyone?

RyanSteele-CoV — Tue, 21 Apr 2026 21:07:40 GMT

Just curious: is the archive mailbox self-help diagnostic at https://aka.ms/PillarArchiveMailbox working for anyone?

When I run it, instead of getting results about the user whose UPN I entered, I get this:

The following issues were found with your archive mailbox.
No account was found for [The UPN of my admin account]. Make sure you've entered the correct email address or create a new account with that name. For more information, see Add users to Office 365.

I tried opening a ticket with Microsoft Support, but they refused to work on it without requiring me to do all the legwork of gathering logs and HAR traces and who knows what else, despite the fact that the support agent was able to replicate the exact same issue in his lab.

User cannot rename categories even when being the owner

mateusz_pawlik_skf_123 — Mon, 20 Apr 2026 10:03:16 GMT

Hi guys,

I have a user that cannot rename categories in a mailbox whilst being the owner.

As you can her permission level is set on owner.

And yet the rename is greyed out:

User says she was able to rename just some time ago, but when she tried on 17/04/2026 she couldn't. Anyone has any ideas?

Email Showing as Quarantined in a Message Trace, but Not Showing up in MS Defender

duntlessOutlook — Thu, 09 Apr 2026 19:23:13 GMT

A customer of ours was waiting on an email to arrive and to help figure out where the email was or if it was sent yet we ran a message trace. The message trace showed that the email was sent to quarantine. With this information in mind, I went to MS Defender > Email & collaboration > Review > Quarantine but could not find the message.

I modified some of the filters and could not get the quarantined message to appear. I triple checked the filters I created and made sure the information was correct. I also removed all filters and looked for the time period the email came in, but could not find it.

Not sure if this is related, but this email had a significant delay likely coming from the sender.

Any thoughts or ideas? Or anything that I am missing?

Administratively retract a user's email

TomCSB — Wed, 08 Apr 2026 12:12:12 GMT

I was recently asked to retract a message that was sent in-error to staff. I ran a discovery/search, and saved it, but when I ran the powershell script after connecting to Exchange, the script could not find the search, something like name not found. I verfied the name was correct, and I am a global admin so permissions should not have been an issue.

Does anyone know of any accurate documentation to run a search and retract? I had to use an old YouTube video and could not find anything in Microsoft's documentation.

ARC verification fail (40) on specific Exchange Online frontends - recurring issue

darkglobe — Mon, 06 Apr 2026 10:56:42 GMT

Hello,
We are observing recurring arc=fail (40) errors on messages forwarded through Exchange Online, caused by specific frontend servers. The same messages pass ARC verification correctly on other providers (Google, etc.).

Affected frontends identified so far:

CH2PEPF0000013F.namprd02.prod.outlook.com - build 15.20.9700.17 (March 14, 2026)
CH3PEPF0000000B.namprd04.prod.outlook.com - build 15.20.9769.17 (April 6, 2026)

Both share the same build suffix .17. The signing implementation on our side has been cryptographically verified as correct and RFC 6376 compliant. The issue has also been reported on the IETF ietf-smtp mailing list with full technical analysis.
Cryptographic analysis shows the failing servers append a spurious trailing \r\n to the last header before computing the verification hash, violating RFC 6376 Section 3.7.

Is there a pattern with .17 frontend builds and ARC verification?

Reagards
Vittorio

Microsoft Exchange Report

atanudutta007 — Sun, 05 Apr 2026 12:27:58 GMT

I faced a new issue today, don't know if anything breaks at Microsoft or any new thing roll out from there, the things is unable to check usage report properly as well as unable to export the email activity, Mailbox Usage etc report under report- exchange and other tabs as well in customer tenant.

I have Global Reader privilege but still facing this issue. Anyone faced this type of issue from today or before? If anyone knows about its pleas update your comment here.

Thanks..

iOS 26.4 iPhone Contact Sync with Microsoft Exchange Online

fbatuns — Wed, 01 Apr 2026 12:59:26 GMT

For the past 2–3 weeks, several of our iOS users have been experiencing synchronization issues with Exchange contacts. Contacts intermittently disappear from their devices and then re-sync after some time. In some cases, the re-synchronization process is significantly delayed. Anyone else experiencing the same issue?

Preserving permissions during EXO migration

Naxiu — Wed, 01 Apr 2026 06:46:40 GMT

Hi,

Can you help me understand the outcome of preserving the permissions in our scenario.

Exchange Server 2016 (soon Exchange SE) in a hybrid with Exchange Online.
We are moving 75% of the mailboxes to Exchange Online.

What ways will preserve or break the full-access or sendas permissions?

I guess best way would be to migrate both the user and the shared mailbox at the same time in the same batch to keep the permission?

If we migrate the user in batch 1 and shared mailbox in batch 2 will that preserve/break the full access/send as?

If we migrate the shared mailbox in batch 1 and usermailbox in batch 2 will that preserve/break the full access/send as?

If the permission is linked directly on the shared mailbox or via a security group is there a difference?

Thanks!

Microsoft Limits App Access to Sensitive Message Properties

TonyRedmond — Thu, 26 Mar 2026 13:43:43 GMT

Microsoft has announced details of a change to app permissions to restrict updates to sensitive message properties (like recipients) without consent for a new advanced mail access permission. If tenants have apps that interact with message properties, including apps developed by third parties, they should check whether the apps are updating sensitive properties. If so, the new permission must be assigned or the apps will stop working.

https://office365itpros.com/2026/03/26/sensitive-message-properties-graph/

Can we hide default address lists in Outlook Address Book and show only custom ones?

Como_L — Wed, 25 Mar 2026 07:05:00 GMT

There are existing Custom Address Lists. When users use the MS Outlook App (Office 2019) and open the Address Book, is it possible to hide the other address lists (including domain-sg-GAL, Global Address List, and domain-sg-Rooms), and only display the Custom Address Lists (domain-HK-AL and domain-sg-AL) — the ones shown in green in the photo?

Issue with certificate renewal for exchange Edge Transport Server

sandiven1154 — Wed, 18 Mar 2026 23:55:05 GMT

Hello team,

I have come across a very particular problem
I deployed 2 exchange server 2019 with one edge transport server

When we are renewing the Certificates with wildcard certificate on both mailbox server ,and on edge transport server ,it is impossible for me to renew the edge subscription

It says the cerificate is in "doublon" (repetitive) on one of the Exchange servers.I have always been using same certificate on exchange server be it edge or mailbox

I tested a bogus different certificate on mailbox and on edge,only then th e edge sync works

Did anybody come across this issue.

Thanks

Disabling Tenant-Wide Auto-Archiving in Exchange Online

IT_Bee — Wed, 18 Mar 2026 11:37:26 GMT

Hello,

I need to disable auto-archiving for Exchange Online mailboxes at the tenant level. Before I pull the trigger, I would like to make sure I’m looking at the right knobs and understanding the downstream effects.

Where is the definitive On/Off switch for auto-archiving at the tenant level (Admin Center vs. PowerShell)?

What is the actual functional difference between the Archive settings in Org Settings and a standard Retention Policy?

If I disable the tenant-wide auto-archiving, what happens to the mail that is already sitting in users' archive mailboxes? Does it stay put, or does it try to merge back?

Thank you in advance.

OAB download fails after hybrid mailbox move.

LainRobertson — Sat, 14 Mar 2026 05:12:28 GMT

Hi folks,

I'm posting this query here as I doubt anyone in the Outlook forums would have the necessary Exchange hybrid knowledge.

I run a classic hybrid Exchange environment where Exchange Server 2019 CU15 is the on-premise platform. Authentication is provided by on-premise AD FS, with the accounts being synchronised from on-premise via AAD Connect.

I've just moved my on-premise mailbox to Exchange Online via New-MoveRequest and for the most part, everything is fine.

One thing that possibly isn't fine - going off the Bits-Client event log is the regular offline address book downloads, where I'm seeing regular failures in the event log and through double-checking with bitsadmin.exe. The initial address book synchronisation worked as the view in Outlook is fully populated, however, I expect that future changes likely won't come through.

bitsadmin output

Event log output

(There's numerous events to choose from - this is the one I'm most curious about.)

The BITS service provided job credentials in response to the UNIDENTIFIED authentication challenge from the outlook.office365.com server for the Microsoft Outlook Offline Address Book <guid> transfer job that is associated with the following URL: /OAB/<guid>/oab.xml. The credentials for the <sid> user were rejected.

When the mailbox was on-premise, the OAB came from the Exchange Server - no surprise there, where post migration it can be seen from the bitsadmin output it now comes from outlook.office365.com. Perhaps that's also to be expected - I don't know, but it makes sense given the move.

What alerted me to there potentially being an issue is the systray icon frequently gets stuck on the "synchronising" icon, and running a manual full OAB sync from within Outlook fails to complete. After an extended "hang" period, the sync window eventually times out with the error shown above (the protracted UI behaviour would appear to be due to the large number of retries).

Dropping the BITS job URL into Edge simply returns a HTTP 503, which doesn't necessarily strike me as a problem. After all, I'm unable to provide a BEARER token using this method. I haven't yet tried via PowerShell as it only occurred to me now but perhaps I'll do so after posting this.

Searching on this error and scenario has turned up nothing useful. I have also checked and compared event log entries from an Azure AD-native account, where it's a mixed bag of successful OAB BITS downloads and unsuccessful ones that feature the same symptoms as above, which offers up the possibility this might be a transient service-side error (though I'm not leaning heavily towards this).

Has anyone else encountered this issue and resolved it? Is it even an issue to begin with, or is this expected behaviour?

I'm unsure what to make of the symptoms.

Cheers,

Lain

Add-PublicFolderClientPermission: Object reference not set to an instance of an object.

AlexFranco — Fri, 13 Mar 2026 15:45:50 GMT

Running into an issue with adding public folder permissions in Exchange Online. I've used this PowerShell script for a few years without any issues, but suddenly getting this error no matter what I try. I do have Owner permissions and there are Default and Anonymous permissions on the public folder, tried completely removing and reinstalling the ExchangeOnlineManagement module as well.

Anyone else having this problem?

$PF = Get-MailPublicFolder -Identity "\pf1" $User = Get-User -Anr "User1" $AccessRights = @( "ReadItems", "CreateItems", "EditOwnedItems", "EditAllItems", "FolderVisible" ) Add-PublicFolderClientPermission -Identity "\$($PF.Id)" -User $User.UserPrincipalName -AccessRights $AccessRights -Verbose

VERBOSE: Returning precomputed version info: 3.9.2
VERBOSE: Requested HTTP/1.1 POST with 227-byte payload
VERBOSE: Received HTTP/1.1 response of content type application/json of unknown size
VERBOSE: Query 1 failed.
Add-PublicFolderClientPermission: Object reference not set to an instance of an object.

Thank you