The built-in back-off mechanisms in the indexing component of Windows Search or WDS pauses the indexing of Outlook data when the system is under heavy use. The easiest way to let the indexing finish is to leave Outlook running overnight. Additionally, you can reduce performance issues by running Outlook in Cached Exchange Mode.

If Outlook for Mac is running slowly, you might try moving messages out of the inbox or turn off logging. This article explains.

The more email you send and receive, the larger your Outlook mailbox can grow. Large mailboxes can take longer to open and search, and many email providers, including Microsoft 365, limit the maximum size of your mailbox. If you receive a message that your mailbox is over its size limit, deleting messages and folders can help, but if you store your information in an Outlook Data File (.pst) or ...

Occasionally, classic Outlook tries to run a process in the background. Auto-archive, sending and receiving a very large attachment, or running some of the other mailbox tools can all be done in the background.

What is the Mailbox Quota Exceeded error? How do I free up mailbox space in Outlook? Build a personal guide for Mailbox Quota Exceeded.

To see how much mailbox storage you've used and quickly clear up space: At the top of the page in Outlook on the web, select Settings > Account > Storage. Clean up Mailbox From the Settings > Storage page you should see a breakdown of how much space each folder in your mailbox is taking.

What's the best way to manage mailbox size in Outlook? What if I can't recover deleted folders in classic Outlook? Manage my mailbox size in Outlook for me. Are you getting weekly or even daily messages warning that you're about to run out of mailbox space? Mailbox Cleanup is a one-stop-clean-up tool you can use to trim the size of your mailbox.

Send large files by using file sharing, cloud services, or other solutions for working around file size limits in Outlook.

This article describes how to troubleshoot Microsoft Outlook when it's used together with Microsoft 365 and: Outlook stops responding (hangs). Outlook crashes even though you aren't actively using it. Outlook crashes when you start it. Try steps 1 through 3 in order until the issue is cleared. If you go through all of those steps and Outlook is still crashing or not responding, complete step 4 ...

Did you get an Outlook not responding error? Is Outlook stuck on a screen that simply says "Processing"? Or does Outlook freeze or stop working when you're opening a file or sending an email message? There are a number of possible reasons for Outlook to behave this way. We've presented the potential solutions in order from quickest to most time consuming.