Add shared mailbox outlook app authentication failed. The truth? It’s not as complicated as it seems—once you know the right path. Feb 23, 2025 · The specific issue was that a few of our users were not able to add a recently created shared mailbox in Office 365 to their Outlook mobile app on Android. I can't install the Outlook app Feb 2, 2024 · SASL XOAUTH2 authentication for shared mailboxes in Office 365 In case of shared mailbox access using OAuth, an application needs to obtain the access token on behalf of a user but replace the userName field in the SASL XOAUTH2 encoded string with the email address of the shared mailbox. Shared mailboxes or delegated calendars do not change this account context. When I try to add a shared mailbox that I full delegate access to, I get the message ‘Authentication failed that didn’t work. That didn't work. We get an error message which says something like "either the mailbox doesn't exist or you don't have permission to use it. What Are Shared Mailboxes? Aug 6, 2025 · If you cannot add your account to the new Outlook app in Windows 11/10, this post will show you how to fix the issue. Outlook known issues in the June 2017 security updates Last updated: July 11, 2017 The issues documented in this section have been reported after installing the recent updates listed below. Oct 25, 2022 · They are able to add the shared mailbox in OWA and O365 desktop app without issues but when they try adding it in the mobile app, they receive the following message: Authentication Failed. zqai rcvjbvpyc udmssb mzogp rquy vcqlrn ijzo kxhrdk pcguc ultj