Outlook

When you use Outlook with multiple Microsoft 365 tenant accounts, you may find that Outlook sometimes picks the wrong tenant identity when composing or replying to messages. This happens because Outlook remembers multiple sign-in tokens and can auto-select an unintended account. This article explains how to bind your Outlook identity to a specific tenant so … Read more

In Outlook for Windows, the Sync to Cloud option appears greyed out when you right-click an IMAP account folder. This setting is intended for accounts that sync mailbox data through Microsoft servers, such as Microsoft 365 or Exchange accounts. IMAP accounts connect directly to your email provider and do not use Outlook.com cloud storage for … Read more

Exchange resource accounts let you book conference rooms, equipment, and shared spaces directly from Outlook without needing a separate tool. These accounts appear as calendar entries you can add to meeting invitations, and they automatically accept or decline requests based on availability. This article explains what resource accounts are, how to set them up in … Read more

When you wake your Windows 11 or Windows 10 computer from sleep, Outlook may display an authentication window with the message “Need Password” even if you previously saved your credentials. This repeated prompt interrupts your workflow and suggests that the stored authentication token did not survive the sleep cycle. The root cause is typically a … Read more

When you add a public folder mailbox to an Outlook profile that uses Cached Exchange Mode, the public folder hierarchy may not appear automatically. This happens because Outlook caches the folder list from the primary mailbox but does not always sync the public folder mailbox data without manual configuration. This article explains how to add … Read more

Microsoft Outlook uses authentication libraries to connect to Microsoft 365 services. The older Azure Active Directory Authentication Library, called ADAL, is being replaced by the Microsoft Authentication Library, called MSAL. ADAL will stop working with Exchange Online in 2025. This article explains the difference between ADAL and MSAL, why MSAL is the required authentication path, … Read more

You need to remove an email account from Outlook but keep the locally stored PST file and its folders, contacts, and archived messages intact. Outlook caches account data in an OST file, which is tied directly to the account and becomes inaccessible after removal. This article explains how to safely remove a cached account while … Read more

You see a yellow banner at the top of Outlook that says Need to Reauthorize even after you have signed in successfully. This banner blocks access to your mailbox and prevents sending or receiving email. The problem is caused by a corrupted or expired authentication token that Outlook uses to verify your identity with Microsoft … Read more