mail@mydomain is causing a cert mismatch error in all browsers for Outlook.com
Hello, I have created a CNAME for our users in my domain so that they can access webmail. For example, it's called mail.mycustomdomain.com, and it is directed to Outlook.com But when I try to visit mail.mycustomdomain.com, it shows a security warning and recommends going back. I can understand because the SAN name in the certificate presented by Outlook doesn't include my CNAME. Is there anything I can do as a workaround so our users can enter the CNAME without encountering a Certificate Mismatch Error? It is causing repeated calls to the helpdesk, and we would like them to use something simple they can remember. Thanks
Outlook Desktop users continually prompted for credentials On-Prem Exchange SE
Battling ongoing issues with users being continually prompted for password using Outlook 2024 LTSC with on-prem Exchange 2019 SE. Removed Windows credentials, turned off cache mode, removed shared calendar(s), outlook connection status seems fine. Only (temp) workaround seems to be removing mail profile and recreating it. All other network resources on domain are fine. Any input appreciated. Thanks
Feature Request: Add "Recent Activity Feed" combining Sent & Received emails
Respected Outlook Product Team, I am writing to submit a feature request aimed at improving productivity and message tracking for power users who heavily rely on Microsoft Outlook for their daily communication workflows. The Problem: Currently, Outlook separates communication into distinct folders: "Inbox" for incoming mail and "Sent Items" for outgoing mail. When managing large-scale communications—specifically when sending bulk or recurring emails via BCC (Blind Carbon Copy)—it becomes incredibly tedious to constantly switch back and forth between the Inbox and Sent Items folders to track recent operations or verify the exact sequence of historical activities. The existing "Group messages by conversation" feature also fails to merge these independent outgoing streams seamlessly unless a direct reply is received. The Solution / Feature Proposal: I highly request the product team to introduce a "Recent Activity Feed" filter or view within the main Outlook Inbox interface. Inspired by modern social media and collaboration timeline feeds, this feature should display both Sent and Received emails chronologically in a single unified message list. Incoming and outgoing messages should be clearly distinguishable using intuitive icons (e.g., incoming/outgoing arrows) and labels (e.g., "SENT (BCC)" vs "RECEIVED"). This will allow professionals to review all recent actions, sent bulk updates, and incoming threads at a single glance without breaking their operational focus. I have attached a UI/UX Concept Design image with this email to visually demonstrate how this feature would streamline the user experience seamlessly. I sincerely hope the engineering and product management teams will consider this feature in future Microsoft Outlook updates to adapt the platform to modern, high-volume workflow requirements. Thank you for your time and continuous efforts to improve Microsoft Outlook. Regards, Pawan Kumar
Exchange SE HU6: PDF attachments truncated to 13 KB via Outlook Desktop — OWA unaffected
We've spent days isolating this and ruled out everything we could touch. The corruption survives agent disabling, Bitdefender removal, and BypassFiltering — and the message tracking logs show exactly where it happens. Environment: Exchange Server SE, Build 15.2.2562.41 (HU6 / KB5081755), Windows Server 2025 Problem: PDF attachments sent internally via Outlook Desktop (MAPI) arrive corrupted at ~13 KB (original: ~32 KB, no xref/EOF). All PDF sizes, all internal recipients affected. Started 21 May 2026. Key finding — OWA works, Outlook Desktop doesn't: Sending the identical email via OWA → attachment arrives intact. Outlook Desktop → truncated. Message tracking proof: Both paths deliver the message at full size (~42 KB) via STOREDRIVER DELIVER. Only the Outlook Desktop delivery shows an additional X-SDDS=0.106 step in the STOREDRIVER latency breakdown. That step does not appear in the OWA delivery. The corruption happens inside that MAPI/TNEF store write step — not in transport. Systematically ruled out: All transport agents disabled → still 13 KB Exchange Malware Agent + Set-MalwareFilteringServer -BypassFiltering $true → still 13 KB Bitdefender GravityZone fully uninstalled from server → still 13 KB EEMS mitigations: only PING1 and M2.1.0 applied, neither affects MAPI delivery Temporal correlation: Three Windows updates installed 21.05.2026: KB5087051 (.NET Framework 4.8.1), KB5087539 (Windows Server 2025 CU), KB5089717 (Servicing Stack). Exchange SE HU6 (KB5081755) was installed around the same period. Workaround: Sending via OWA works. Not acceptable long-term. Has anyone seen this? Is this a known regression in HU6 or KB5087051?
Is Office 365 E3 Developer free
Hi, My tenant had a license named "Office 365 E3 Developer" which allowed us to use Outlook / Exchange (among other Microsoft Office products). This license isn't from the Microsoft 365 Developer Program, which come with free licenses. This license costed CA$11.60 a month per user when we initially purchased it. On May 2, 2026 it still costs $11.60, but when I received my monthly invoice for this tenant, this license was free. I searched around to see whether this license became free recently, but I couldn't find any info on this. The links I found all say it's a paid license. I was wondering if there's any info on this to see why it became free? Or is it a mistake and Microsoft'll be charging us the next billing cycle? JasonFIX - Outlook 2013,2016,2019 fails open mailbox Exchange 2019 on-prem in offline LAN
Exchange 2019 on-prem + Outlook 2013/2016/2019 in offline LAN Symptoms: - OWA works - ECP works - Autodiscover works - Test-MAPIConnectivity is successful - Outlook profile can be created - Outlook fails to open the mailbox / “Cannot start Microsoft Outlook” / “The set of folders cannot be opened” / “The attempt to log on to Microsoft Exchange has failed” - Environment has no internet connection Root cause: The Windows client had a default gateway configured, but the gateway IP did not respond to ping. In our case the client received 192.168.1.1 as default gateway, but this IP was unreachable in the offline network. Fix: Set the client default gateway to an existing reachable IP address, for example the Exchange/DC server IP 192.168.1.5. Internet access is not required, but the default gateway must be reachable/responding. After changing: Default gateway: 192.168.1.5 DNS: 192.168.1.5 mail/autodiscover DNS or hosts pointing to Exchange 2019 Result: Outlook 2013, Outlook 2016 and Outlook 2019 connected to Exchange 2019 successfully.Migration from Hosted Exchange (Hybrid) to M365 Classic Outlook Client Problems and Solutions
Hello Everyone, I'm a tech who started on a 8088 processor in the 80's. Not mentioning the Vic20 and C64 since that hardly seem relevant! I'm posting here to hopefully help the next person with the issues I've had over the last few weeks. My client had to port his email from a provider with an on-perm Exchange server in a Hybrid setup with M365 to his own M365 environment. I expected this was to be about 3 hours of work for me - setup M365 environment, plan the cut-over window, update the Outlook clients on each PC. It ended up being roughly 20 hours of my time and at least 10 hours of dedicated time for my client. For those wanting to jump directly to what mostly fixed it use this link, it should get you past the dreaded "an encrypted connection to your mail server is not available" when trying to add the mail account into a clean profile. Use https://support.microsoft.com/en-us/windows/classic-outlook-troubleshooters-086e3d66-5404-4034-9cc5-545909dcc166 and pick "Classic Outlook Profile Setup Troubleshooter" Most hits are going to tell you its an autodiscovery issue, but if you're reading this I'm going to assume you've already confirmed that. Our issue was some ghost configuration, only on the PCs previously setup for mail on the old server. A new PC could add the same account without issue. Some of the research suggested this would not happen if the proper Microsoft migration process is followed to move the account - but in our case the previous provider was unable to perform the migration. I'll skip over the research we tried along the way, such as New Outlook Profiles, Registry entry changes, MS Personal users with the same email as MS Business Users, Autodiscover problems (including concerns that the base website for the client was offering invalid data), and so on. After each hit where we applied a fix we again had to try adding the mail to the profile, and each time we sat watching the little circle for up to 5 minutes only to get the same error. Now, once we found the link above - which did not come up in most searches - things got better, but not 100%. We added the profile ok but then Outlook gave a permission error while starting. To fix that, the user signed in must have administrative access and you use File Explorer to navigate to the folder identified in the error. In our case it was in folders kept under \Windows\System32\. When prompted that we need to grant permanent access we said yes. In our case this is where Outlook was storing the ost files. That worked for most of the clients, but we had one additional issue where the error was pointing to a folder that didn't exist. Just creating the folder was not enough, the final fix was to hold CTRL-SHIFT down while opening Outlook to start in administrative mode to allow it to create the ost file in the newly created folder. Finally 3 weeks after our cut over window, while the client had to use OWA, we were able to get outlook running. This was critical for my client because they did not have access to the mail history since the migration didn't happen - they had to open a copy of their PST in Outlook and use mail in OWA and constantly bounce back and forth. I hope this helps someone avoid the pain we went though!
