How to Clear Cache in Outlook on Phone, Mac and Windows

When Outlook starts misbehaving, with emails missing, folders that won't update, or an old wrong address popping up every time you type a name, someone will tell you to clear the cache. It's decent advice, but Outlook has several different caches, and the button for each one depends on whether you're on a phone, a Mac or Windows.

I've gathered what Microsoft's help pages say for each, including the one place where there's no official cache button at all. Read the warnings before you start, because one of these steps can delete anything that hasn't synced.

Which Outlook cache is causing your problem?

What you're seeing	Cache to clear
Wrong or old addresses suggested as you type	The AutoComplete or suggested contacts list
Missing or out-of-date emails in the phone app	The mobile app cache or Reset Account
Folders not syncing in Outlook for Mac	The Exchange folder cache

Clearing the Outlook app cache on Android

Microsoft's mobile troubleshooting page gives these steps, and says your data will be kept:

1. Open your phone's Settings, go to Apps, then Outlook, and tap Force stop.
2. Still in Apps, Outlook, open Storage and tap Clear cache.
3. Update Outlook from the Google Play Store if an update is waiting.
4. Restart your phone and open Outlook again.

Refreshing the Outlook app on iPhone

There's no separate clear cache button for apps on an iPhone. Microsoft suggests closing Outlook from the app switcher, restarting the phone and updating Outlook from the App Store. If that doesn't help, you can offload the app under Settings, General, iPhone Storage, Outlook, Offload App, then reopen it.

Resetting an account inside the Outlook mobile app

For incomplete or incorrect data on Android or iPhone, Microsoft's first step is to force close and reopen the app. If the problem stays, open Outlook, go to Settings, select the email account and tap Reset Account. It's the closest thing the app has to a fresh start for that mailbox, and it's worth trying before you delete and reinstall anything.

Emptying the cache in Outlook for Mac

This one applies to Exchange accounts, which is what most work and Microsoft business email uses. Microsoft's steps:

1. Check your Mac is connected and online.
2. In the folder list, Control-click or right-click the Exchange folder that's misbehaving and choose Properties.
3. On the General tab, select Empty Cache.
4. Wait while Outlook downloads the folder's items again from the server.

The warning matters here. Microsoft says this deletes any information that isn't synchronised with the Exchange server, including contacts' mail certificates, so back up your Outlook data first. If you've drafted something offline that hasn't synced, it could vanish.

Clearing Outlook's AutoComplete name cache

If Outlook keeps offering an old email address for a client, the name cache is the culprit. In classic Outlook for Windows, go to File, Options, Mail, find the Send messages section and select Empty Auto-Complete List. Microsoft also describes starting Outlook with the /CleanAutoCompleteCache switch, though the menu route is easier for most people. Outlook on the web keeps its own separate list, so clearing one doesn't clear the other.

For work or school accounts, many suggestions come from Microsoft's own contact discovery. Microsoft says you can clear those from your account's privacy settings: on the Privacy tab, expand Manage contact suggestions and discovery, then select Clear data under Discovered contacts. It doesn't delete your organisation's directory or your personal contacts. With a personal Microsoft account, Microsoft points you to the People suggestions toggle on your privacy page instead.

What about new Outlook for Windows?

Here's the honest answer: Microsoft's help pages don't give a clear cache button or folder for new Outlook for Windows. I'd steer clear of guides that tell you to delete hidden app folders by hand, because you can lose settings or unsynced items. What you can do is restart Outlook and your computer, make sure Outlook is up to date, and check whether the same problem shows in Outlook on the web. If it looks fine on the web, the problem is with the app on your computer, which gives whoever supports your IT a useful clue.

Before you clear any Outlook cache

• Make sure anything important has synced, especially drafts.
• Back up your Outlook data if you're on a Mac with Exchange.
• Try the gentle fix first: close Outlook fully and reopen it.
• Check your internet connection, as many sync problems are simply that.

Keeping Outlook running smoothly for your business

A crowded mailbox makes every app work harder. Archiving old threads keeps the inbox light, and my guide to archiving emails in Outlook shows how without deleting anything you might need. If junk mail is a big part of the clutter, blocking emails in Outlook stops repeat offenders before they fill your folders again.

Frequently asked questions

Does clearing the Outlook cache delete my emails?

On Android, Microsoft says clearing the app cache keeps your data. In Outlook for Mac, Empty Cache deletes anything not synchronised with the Exchange server, so back up first.

How do I clear the cache in the Outlook app?

On Android, go to Settings, Apps, Outlook, Storage and tap Clear cache. In the app itself, you can also go to Settings, select the account and tap Reset Account.

Is there a clear cache button in new Outlook for Windows?

Microsoft's help pages don't give one. Restart Outlook, update it and check Outlook on the web to see whether the problem is with the app.

How do I stop Outlook suggesting an old email address?

In classic Outlook, go to File, Options, Mail and select Empty Auto-Complete List. For work or school accounts, clear discovered contacts in your privacy settings.

How do I clear the cache in Outlook for Mac?

Right-click the Exchange folder, choose Properties and select Empty Cache on the General tab. Outlook then downloads the items again.