Fixes or workarounds for recent issues in Outlook for Mac

Outlook 2016 for Mac Outlook 2019 for Mac
Last updated: May, 2021

Outlook for Mac features, add-ins, and know issues

• [FIXED] Outlook for Mac crashes unexpectedly on startup or during mail synchronization
• [WORKAROUND] Characters are garbled in email body
• [WORKAROUND] Error -17099 or -3253 when trying to send an email with an attachment
• [FIXED] Search in Outlook for Mac returns limited or no results for macOS Big Sur
• [FIXED] Send button is greyed out and prevents sending an email
• [WORKAROUND] Message body of an .eml attachment is blank in Preview
• [FIXED] Changing "Arrange By" sort option affects all folders in Outlook for Mac
• [FIXED] Interacting with attachments from the drop-down menu causes unexpected behavior in Outlook for Mac
• [FIXED] iMac screen flickers when using Outlook for Mac
• [FIXED] "Unsupported version of WebEx plugin is detected" message
• [FIXED] Search doesn't work in Outlook for Mac after MacOS upgrade

Unable to attach files over 25M in Outlook for Mac using IMAP or POP [WORKAROUND]

Changed functionality and blocked or discontinued features

• Outlook for Mac 2011 does not work with macOS 10.15 Catalina
• Sending meeting updates with REST calendar sharing feature in Outlook for Mac
• Categories no longer appear in the sidebar of individual calendars
• Known issues syncing Google accounts to the Microsoft Cloud

Automated troubleshooting tools

Use the following tools to resolve various Outlook for Mac issues. See this page for more information and learn how to install the tools: Outlook for Mac support tools.

Outlook Search Repair Note: This tool doesn’t work on macOS 10.14 and later. Check Outlook for Mac support tools article here for more details.	This tool repairs search issues in Outlook for Mac. For example, when search returns no results for items that do exist in your mailbox, or you get older data when you have newer items.
Outlook Reset Preferences	This tool resets customization that you've made to Outlook from the Outlook menu > Preferences. It also restores Outlook window size and position settings.
Set Default Mail App	This tool lets you choose Outlook for Mac as your default mail application. Then Outlook opens a new email whenever you click on a mailto: link in an email or website.
Reset Recent Addresses	This tool lets you reset recent addresses that Outlook has stored, and delete recent addresses all at once, instead of one at a time.