Resolving “Outlook Mailbox Full” Issue: The Ultimate Guide

Why Do I See the “Outlook Mailbox Full” Error?

Maybe you’re expecting an important message or need to send an email immediately and see a message that your Outlook is full. Your feeling of popularity at receiving so many emails is short-lived because you’re now stuck. What does this message mean and what can you do about it?

If you see a “Your mailbox is full, you may not be able to send or receive items” or similar message in Outlook, this means you’ve reached the storage limit for your mailbox. That’s right, there’s not an infinite amount of space—every user has limited email storage.

Currently, free Microsoft Outlook accounts receive 15 GB of storage, and Microsoft 365 subscribers have 100 GB. All emails and attachments across all folders count towards the Outlook email storage limit including the Sent and Deleted folders.

So, how do you regain mailbox storage space in Outlook? Basically, it’s time for some email cleaning and we’re here to guide you through it using both the email service and the Clean Email app.

Where to check storage

• Outlook on the Web (Outlook.com / new Outlook):

Go to Settings (gear icon) → Accounts → Storage. From here, you can see your current usage and select Clean up mailbox to quickly delete items older than 3, 6, or 12 months. Don’t forget to empty the Deleted Items folder — it still counts toward your limit.

• Outlook Desktop (Windows/Mac):

In the Outlook app, click File → Tools → Mailbox Cleanup. This panel lets you view the size of each folder, find and delete large items, and set up AutoArchive rules to prevent future overflow.

Best Ways to Fix Outlook Mailbox Full Storage

We’ll walk you through several basic and advanced Microsoft Outlook tips for returning storage space to your mailbox. For Outlook on your desktop, the web, and your account in Clean Mail, you’ll be back in business with emails flowing in just minutes.

Fix full storage in Outlook on the desktop

If your preferred method for using Outlook is the desktop application, you can use the built-in Outlook mailbox cleanup tool.

1. Open the desktop application and go to the File tab.
2. Select Info and open the Tools menu to pick Mailbox Cleanup.
3. You’ll see a handful of options to clean up your mailbox and regain some storage space. You can locate and delete old emails in Outlook, use the AutoArchive feature, empty your deleted items, and remove conflicts. Simply pick an option and follow the prompts.
4. When you finish, you can choose View Mailbox Size at the top to see the updated amounts. Then, click Close when you’re done.

Consider using these steps to clean up your Outlook mailbox regularly to keep your used storage under control.

Fix full storage on Outlook.com

Maybe you prefer to head to the web to manage your inbox. Although you won’t find the same Outlook cleanup tool as on desktop, here’s how to check your Outlook storage and then get it under control.

1. Visit https://outlook.live.com/mail and log in with your Microsoft account.
2. Select the Settings gear icon on the top right.
3. In the pop-up window, choose General on the far left and Storage to the right.
4. On the far right, expand the Email storage option. You’ll see your total storage amount along with how much you’ve used. You can also view the color-coded graph for which sections of your email account use the storage.
5. Beneath Manage storage, you can empty folders such as Junk Email, Deleted Items, Sent Items, and others. Conveniently, you’ll see how much storage the folder uses and the number of messages within it.
6. For a more precise approach, open the Empty drop-down menu to the right and pick All or choose an option like three, six, or 12 months and older.
7. Select OK when the confirmation box appears and check out your updated mailbox size.

Remember, you can perform the above steps on a regular basis to better manage your storage and organize Outlook emails wisely.

Fix full storage in the Outlook Mobile app

On the Outlook mobile app, you can free up space almost as easily as on desktop or web. Start by adjusting your swipe settings.

Go to Settings → Mail → Swipe Options, and set your Swipe Action to Delete for faster cleanup.

Make sure to check the Junk and Deleted folders as well. Even on mobile, messages stored there still count toward your limit until you remove them completely.

Attachments are another common cause of a full mailbox. Open any message with large files, save the attachments to your phone or cloud storage, and then remove the email entirely.

If you want to pinpoint the biggest space hogs, use the search bar to look for emails with attachments or sort messages by size.

Fix Full Outlook Storage With Clean Email

While the cleaning tools Microsoft provides for Outlook on the desktop and web may be sufficient for freeing up some space, you can take your cleanup a step further with Clean Email. With it, you can automate the cleaning process to eliminate that dreaded “Outlook inbox full” message in the future.

Additionally, you can try Clean Email for free and take advantage of its other tools for keeping your inbox tidy and secure. Because Clean Email works with Outlook.com accounts, it’s a convenient and effective supplementary solution.

💡 Tip: If you use Outlook on your mobile device, check out the Clean Email app for Android and iPhone. You can enjoy effortless email management in a safe and secure inbox when you’re on the go.

Auto Clean

With Auto Clean, you make the rules. Set up the conditions for incoming messages and let Clean Email automatically move, flag, trash, or send emails to spam.

1. Select Auto Clean on the left, turn on the Auto Clean toggle on the right, and choose Create Rule or the plus sign at the top.
2. Give your rule a name and select one or more conditions. For example, you can pick emails you composed by never sent in the Drafts folder, messages you receive from a particular sender or domain, or emails older than one year.
3. Choose the action you want to apply to those emails meeting your condition(s). For instance, you can move them to the trash, mark them as spam, or delete them.
4. Select Create Rule at the bottom when you finish.

By using Auto Clean in Clean Email, you can simply ‘set it and forget it’. Instead of manually cleaning your mailbox on a schedule, just spend a few minutes upfront creating automations that do it for you. Later, you can then keep track of your running rules in the Auto Clean section or access them through the Control Center.

Cleaning Suggestions

Maybe you receive so many emails that you simply don’t know where to start. If your Outlook mailbox is full, you can view the app’s Cleaning Suggestions for ways to clean it up.

Select Suggestions on the left to see a list options suggesting to clean similar messages. Here, you can perform the recommended action to the right, pick a different one in the drop-down menu, or just dismiss the suggestion.

Whenever you sign in to Clean Email, you’ll see the number of Suggestions in the left-hand menu. Check out those recommendations frequently for help with your Outlook email management.

Unsubscriber

Signing up for newsletters sounds fun in the beginning, but the more you subscribe to, the more space they take up when they arrive in your mailbox. You can use the Unsubscriber tool to remove yourself from mailing lists.

Select Unsubscriber on the left and then manage those emails on the right. You can choose Unsubscribe to discontinue receiving them or Pause to stop them temporarily (the app will move the incoming messages to trash).

Smart Folders

To keep your mailbox organized and help you manage emails in bulk, Clean Email provides you with Smart Folders. These 33 predefined filters place emails into folders automatically letting you then move, delete, or mark them as spam in one fell swoop.

Expand Smart Folders on the left and then choose a folder to view the contents. For example, you might open the Online Shopping folder and decide to delete a bunch of emails within it, or even all of them.

You can also filter, group, and sort the emails in a Smart Folder for further exploration. And keep in mind, these Smart Folders can help you regain space quickly. For instance, you can delete multiple emails in Outlook using a single Smart Folder.