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Mozilla has released Thunderbird 145, introducing full native support for Microsoft Exchange email accounts via the Exchange Web Services (EWS) protocol. This update allows Thunderbird users in Microsoft Exchange environments, such as Microsoft 365 and Office 365, to connect directly without relying on third-party add-ons or IMAP/POP protocols. The new integration supports seamless message synchronization, folder management, attachment handling, and uses Microsoft’s OAuth2 authorization protocol for secure authentication.
The update also simplifies migration from Outlook to Thunderbird, as the email client can now automatically detect Exchange settings and guide users through the setup process. Supported features include viewing, sending, replying, forwarding, moving, copying, and deleting messages, as well as advanced search and quick filtering. This enhancement positions Thunderbird as a viable alternative to Outlook for organizations using Microsoft Exchange, improving flexibility and user choice in enterprise email environments.
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Mozilla Thunderbird introduced native support for Microsoft Exchange accounts, enabling users to connect Exchange mailboxes directly without relying on add-ons or workarounds. The change was highlighted as making migration from Microsoft Outlook to Thunderbird easier.
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Mozilla published advisory **MFSA 2026-94** detailing security vulnerabilities corrected in **Thunderbird 156**. The associated Mozilla Bugzilla records, including bugs `2057121` and `2056051`, are access-restricted, so technical vulnerability details and impact information are not publicly available in the referenced material. Organizations using Thunderbird should upgrade deployed clients to version 156 through their normal software-management process and verify that older installations are remediated. Security teams should track Mozilla’s advisory for any later disclosure of CVE identifiers, affected configurations, severity ratings, or exploitation information.
Sep 21, 2026
Microsoft moved to resolve two separate email access problems affecting Outlook and Exchange Online users. In Exchange Online, a newly introduced **virtual account** change intermittently blocked some users from accessing cloud mailboxes through Outlook mobile apps and the new Outlook for Mac, prompting Microsoft to classify the issue as a service outage under `EX1256020`. After infrastructure restarts failed to restore access, the company identified the change as the root cause and began disabling it across affected environments. Microsoft also fixed a classic Outlook bug that caused Gmail and Yahoo accounts to stop synchronizing, triggering errors `0x800CCC0F` and `0x80070057` after users stopped receiving sign-in prompts. The company said the service-side fix was deployed, but some users could continue seeing sync failures until their OAuth token expires, such as after a password change. Microsoft published a temporary workaround to force a new sign-in prompt and noted it is still investigating other Outlook-related problems, including Exchange Web Services group creation failures and a Teams Meeting Add-in issue that can make classic Outlook unusable.
Jun 29, 2026
Microsoft released **KB5121611**, the September security update for Exchange Server 2016 CU23, addressing seven vulnerabilities: `CVE-2026-69355`, `CVE-2026-69356`, `CVE-2026-69361`, `CVE-2026-69375`, `CVE-2026-69378`, `CVE-2026-69382`, and `CVE-2026-69641`. A security advisory from Gambia’s national CSIRT characterized the Exchange Server issue as a pre-authentication remote-code-execution risk. The update also fixes a hybrid-deployment issue that caused wrapper messages to appear in shared mailboxes following the June 2026 security update. Microsoft cautioned that published calendar `.ics` files may return HTTP 500 errors after installation; Exchange Server 2016 and 2019 are out of support, with updates available only to organizations in the Period 2 Extended Security Update program through October 2026, and organizations should migrate to Exchange Server Subscription Edition.
Sep 9, 2026