The Outlook mobile app can consume significant storage on your phone, slowing down performance and filling up space. This is typically caused by cached email data, downloaded attachments, and offline calendar files. This article provides steps to clear this cached data and adjust settings to prevent future storage bloat.
You will learn how to manage attachment storage, limit offline mail periods, and clear the app’s local cache. Following these methods can free up several gigabytes of space on your device.
Key Takeaways: Reducing Outlook Mobile Storage
- Settings > Storage: The primary location to view storage usage and clear cached data for all accounts.
- Attachment Storage Settings: Controls where attachments are saved and automatically removes old downloads.
- Mailbox Settings > Sync Settings: Limits the amount of email downloaded to your device by adjusting the sync window.
Why the Outlook App Uses So Much Phone Storage
The Outlook mobile app stores data locally to provide fast access to your emails and calendar when you are offline. This cached data includes email message bodies, file attachments you have opened, and calendar details. Over time, especially with multiple accounts or heavy email use, this local cache can grow to several gigabytes.
The app also downloads attachments to your device’s internal storage by default for quick viewing. If you frequently receive large files, these can accumulate rapidly. Unlike some cloud storage apps, Outlook keeps this data until you manually clear it or until it reaches a storage limit you define.
Primary Storage Consumers
Three main areas use storage: the email cache for offline reading, downloaded attachments, and offline calendar files. The app’s Settings > Storage screen breaks down usage by account and data type, helping you identify what to target for cleanup.
Steps to Clear Cache and Manage Storage Settings
Use the following steps within the Outlook mobile app to reduce its storage footprint. Start by checking your current usage to understand what is consuming space.
- Open Outlook Settings
Tap your profile picture or initial in the top-left corner of the app, then tap the gear icon to open Settings. - Navigate to Storage
In the Settings menu, select the “Storage” option. This screen shows total storage used and a breakdown by account. - Clear Cached Data
On the Storage screen, tap “Clear Cache” or a similar option. Confirm the action when prompted. This removes locally stored email bodies and calendar data but does not delete any messages from the server. - Manage Attachment Storage
Go back to Settings and select “Attachment Storage.” Choose “Smart Storage” to automatically remove older downloads, or set a maximum storage limit. You can also change the default download location to an SD card if your phone supports it. - Adjust Mail Sync Settings
Select your account under “Mail Accounts,” then choose “Sync Settings” or “Mailbox Settings.” Reduce the “Sync email for the past” period from “All” to a shorter time like 1 month or 2 weeks to limit offline email storage. - Review and Delete Large Files
In the main app view, use the search bar to find emails with large attachments. Open such an email, long-press the attachment, and select “Remove Download” to delete the local copy while keeping the email.
Freeing Space for a Single Account
If you have multiple accounts and only one is using too much space, you can manage it individually. In Settings > Storage, tap on the specific account name. You will see options to clear the cache or manage attachments for that account alone without affecting others.
If Storage Usage Remains High After Clearing Cache
Outlook Still Shows High Storage in Phone Settings
Phone system settings may report a different storage size than the Outlook app. This discrepancy is often due to system measurement delays or temporary files. Force close the Outlook app and restart your phone. Then check storage again after a few minutes; the system should update to reflect the cleared cache.
Attachments Keep Downloading Automatically
If attachments continue to fill storage, verify the Attachment Storage setting is not set to “All.” Set it to “Smart Storage” or a specific size limit. Also, disable the “Automatically download attachments” option in the account’s sync settings for cellular data to prevent unwanted downloads.
Cache Refills Immediately After Clearing
A rapidly refilling cache usually means your sync window is set to “All” mail. The app will immediately start re-downloading messages. Permanently reduce storage by shortening the sync period in Mailbox Settings as described in the main steps. This limits the total data the app can store.
Storage Management Strategies Compared
| Item | Clear Cache | Limit Sync Period | Manage Attachments |
|---|---|---|---|
| Primary Action | One-time deletion of offline email and calendar data | Prevents future download of old emails | Controls automatic download and deletion of files |
| Storage Impact | Immediate reduction, but data may return | Prevents long-term growth | Targets largest files directly |
| Data Loss Risk | No server data deleted | Older emails not available offline | Attachments must be re-downloaded to view |
| Best For | Quick cleanup | Preventing the issue | Users who receive many large files |
You can now effectively manage the Outlook app’s storage on your phone. Start by using the Storage screen to clear cached data and review usage by account. For lasting control, adjust the Attachment Storage and Mail Sync settings to set automatic limits. An advanced tip is to use the Focused Inbox, as it syncs fewer emails by default, which can indirectly reduce local cache size.