Last updated: June 2026
Outlook for Mac features, add-ins, and known issues
- [INVESTIGATING] Outlook for Mac fails to send email with SMTP error '-3253' or 'Connection to the server failed or dropped'
- [INVESTIGATING] Replying to or forwarding an email does not include the original message in email body in legacy Outlook for Mac
- [INVESTIGATING] Auto-complete suggestion does not work in Outlook for Mac
- [INVESTIGATING] The Detect Language Automatically feature is not working as expected in Outlook for Mac
- [FIXED] When the reading pane is set to one side or hidden, it is not retained upon re-launch in Legacy Outlook for Mac
- [INVESTIGATING] Outlook for Mac and Outlook Mobile intermittently stop syncing
- [FIXED] Inbox shows incorrect number of unread items in Outlook for Mac
- [FIXED] Subject and body are blank when sending S/MIME emails in Outlook for Mac
- [FIXED] Errors CAA2000B, 4usqa, and 49dvs when trying to sign in to classic Outlook and Outlook for Mac
- [FIXED] Legacy Outlook for Mac emails are not grouped in Conversation threads as expected for Exchange OnPremise/Office 365 and Google accounts
- [FIXED] Outlook for Mac stops syncing when Conditional Access is enabled
- [INVESTIGATING] Some Outlook for Mac and iOS users are seeing a generic shadow.outlook.com email when drafting an email
- [FIXED] Some options are grayed out in the attachment dropdown menu in legacy Outlook for Mac
- [FIXED] Unable to add files as an attachment to emails in Outlook for Mac
- [BY DESIGN] Unable to use the Contact Support option from the Help Menu in Outlook for Mac
- [INVESTIGATING] Unable to assign categories to items in Shared and Delegated Mailboxes in Outlook for Mac
- [FIXED] Unable to add an account in Outlook for Mac
- [FIXED] Microsoft 365 for Mac users in the Beta channel are not offered app updates
- [BY DESIGN] Follow Up flag does not work in outgoing emails in legacy Outlook for Mac
- [WORKAROUND] IMAP Yahoo and AOL accounts might experience issues with re-syncing folder content
- [FIXED] Selecting Reply, Reply All, and Forward buttons is not working as expected
- [FIXED] Outlook fails to send attachments and inline images when sending a signed or encrypted email using Outlook for Mac
- [FIXED] Outlook for Mac stops responding when using the search feature
- [WORKAROUND] Outlook for Mac "Account already exists" error
Click here for older crashes and slow performance issues that are fixed
Note
If you can't find your specific issue in the list below, please try updating Outlook for Mac to the latest version. For more information, go to Update Office for Mac automatically.
- [FIXED] Attachments missing from emails when using macOS Big Sur
- [FIXED] Can't add M365 accounts in Outlook for Mac when the macOS language is set to Turkish
- [FIXED] Can't create new signatures in new Outlook for Mac and existing signatures are missing
- [FIXED] Calendars don't display in the left pane after upgrading to 16.63 build in legacy Outlook for Mac
- [FIXED] Outlook stops responding when viewing Uber receipt emails and some other emails with tables
- [FIXED] Outlook for Mac fails to open attached files if the helper application is already running after installing macOS 11.6.6 update
- [FIXED] To, CC, and BCC fileds are shortened after updating Outlook for Mac
- [FIXED] Search in Outlook for Mac returns no results after installing macOS Monterey 12.1
- [FIXED] The new Outlook for Mac users cannot access Online Archive mailbox
- [FIXED] Outlook for Mac crashes unexpectedly on startup or during mail synchronization
- [FIXED] Characters are garbled in email body
- [FIXED] Error -17099 or -3253 when trying to send an email with an attachment
Changed functionality and blocked or discontinued features
- The Toggle Button to revert to Legacy Outlook Client is missing in Office 2024 Home and Business for Mac
- New location for key functions and direct access to other Microsoft 365 apps in Outlook for Mac
- Missing toggle button in Outlook for Mac
- Legacy Outlook for Mac 2011 does not work with macOS 10.15 Catalina
- Sending meeting updates with REST calendar sharing feature in legacy Outlook for Mac
- Categories no longer appear in the sidebar of individual calendars in legacy Outlook for Mac
- Known issues syncing Google accounts to the Microsoft Cloud
Need more help?
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To report issues or provide feedback, simply go to Help > Contact Support in Outlook for Mac. For more information, see Contact Support in Outlook for Mac. |
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Have a feature request?
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To suggest new features in Outlook for Mac, go to Help > Give Feedback. We're listening. |
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