User cannot rename categories even when being the owner
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?
ARC verification fail (40) on specific Exchange Online frontends - recurring issue
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
Reserve Calendar Time for Bookings
How do you block space out on your personal calendar such that it's only available to Microsoft bookings, and shows busy to others in your organization? I've created a personal bookings page with custom timeslots--that's working just fine. The problem is that people in my org who can see my calendar are sending calendar invites for those same timeslots, making them no longer available to the bookings page. If I add my own events to my personal calendar to mark time as busy, those slots also disappear from the bookings page. How can I adjust things such as to reserve time exclusively for Microsoft bookings and no other users at my org?Improving How Outlook Classic Handles Reactions
A fix due in May 2026 will make sure that the Outlook classic client will handle Outlook reactions properly if the reactions are blocked. Of course, if tenants don’t like responding to email with an emoji, they can create a transport rule to insert the x-ms-reactions header. Detecting the header is an instruction to Outlook clients to suppress reactions that Outlook classic has been ignoring up to now. https://office365itpros.com/2026/04/17/outlook-reactions-classic/Mailbox for Service Account (exchange online)
Hi Our organisation isn't ready to move to Exchange Online yet, though we have Office 365 e3 licencing. I need to create a service account that can send emails via Outlook 365 for use In Power Automate. The documentation I have seen for adding a mailbox to an existing AAD user requires assigning an exchange licence to the account via the licence portal. I can't see any such licences though we do have e3 licencing which are visible that I assume covers this? Unfortunately the admin who did the original configuration has moved on and I don't have a global admin role so have to go through a support team that can't help me with my lack of knowledge in the area! Any advice would be very much appreciated as what ( i think) should be a simple task has taken a lot of time to try and get to the bottom of! Thanks, Dale.
How do I stop Copilot from adding to my Outlook?
I'm using Outlook Classic, and every day Copilot adds itself to my Outlook. I right-click and select uninstall, but the next day it comes right back. I do not want Copilot. How do I stop Copilot from adding to my Outlook. I've included screenshots to see what I'm talking about. Version: Microsoft® Outlook® for Microsoft 365 MSO (Version 2504 Build 16.0.18730.20122) 64-bit
Last week my office changed color to blue and i spoted opening pdf files
Last week my office changed color to blue and i spoted opening pdf files. when i try to open a pdf file says "Error and to try again later in a few moments" The Outlook online say the same thing. On my phone i can see the pdf fine. I tryied to repair the outlook, but didnt work.
Outlook 2016 blank MFA screen for some users
I have a Conditional Access rule so that when someone connects from outside a trusted IP it requires MFA, I have a few users that get the "Requires password" message come up, they get a window and type in their username and click next, then the window disappears without prompting for MFA and it's back to where they were. Same thing if they go to File->Accounts if they are signed out and try to sign in they get asked for Email and then it just closes and they are still signed out. It's not for all users and everyone is using the same Office 365/2016 installation, monthly channel 1903, we use ADFS
