How To Add More Storage To Outlook Email : Email Storage Expansion Options

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Running out of space in Outlook email usually means you need to clear attachments or buy more storage. If you’ve ever seen that dreaded “Your mailbox is almost full” message, you know how frustrating it can be. Learning how to add more storage to Outlook email is simpler than you think, and this guide will show you every practical step to free up space or expand your capacity.

First, let’s understand why Outlook storage fills up so fast. Emails with large attachments, old messages, and cached data all take up room. But don’t worry—you have options. You can clean up what you already have, archive old emails, or upgrade your plan. We’ll cover all of these methods in detail.

How To Add More Storage To Outlook Email

This section covers the most effective ways to increase your Outlook storage. Whether you use Outlook.com, Microsoft 365, or the desktop app, these steps work. Start with the free methods before spending any money.

Clear Out Large Attachments

Attachments are the biggest space hogs. Outlook lets you find and remove them easily. Here’s how:

  1. Open Outlook and go to your inbox.
  2. Use the search bar at the top. Type: hasattachments:yes
  3. Sort by size by clicking the “Size” column header.
  4. Select emails with large attachments (over 5 MB).
  5. Delete them or save the attachments to your computer first, then delete the email.

You can also use the “Mailbox Cleanup” tool in the desktop version. Go to File > Tools > Mailbox Cleanup. This shows you the largest items in your mailbox.

Empty The Deleted Items And Junk Folders

Outlook doesn’t always automatically empty these folders. They can hold gigabytes of data. Do this:

  • Right-click the “Deleted Items” folder and choose “Empty Folder.”
  • Do the same for the “Junk Email” folder.
  • Check the “Spam” folder too.

After emptying, wait a few minutes for the space to free up. Sometimes it takes a sync.

Archive Old Emails

Archiving moves old emails to a separate file (PST) on your computer. This frees up space in your mailbox but keeps the emails accessible. Follow these steps:

  1. In Outlook desktop, go to File > Info > Tools.
  2. Select “Clean Up Old Items.”
  3. Choose a folder to archive (usually your Inbox).
  4. Set a date—archive anything older than 6 months or 1 year.
  5. Click “OK” to create the archive file.

For Outlook.com, you can download old emails as a PST file using the “Export” feature. Then delete them from the server.

Use The “Mailbox Cleanup” Feature

This built-in tool is a lifesaver. In the desktop version, go to File > Tools > Mailbox Cleanup. You’ll see:

  • View mailbox size.
  • Find items older than a certain date.
  • Find items larger than a certain size.
  • Empty deleted items.

Use it to target the biggest space wasters. You can delete or archive them in one go.

Reduce Cached Exchange Mode Settings

If you use Outlook with an Exchange account (like Microsoft 365), cached mode downloads all emails to your computer. This eats up local disk space. To reduce it:

  1. Go to File > Account Settings > Account Settings.
  2. Select your email account and click “Change.”
  3. Under “Offline Settings,” drag the slider to “1 month” or “3 months.”
  4. Click “Next” and restart Outlook.

This only affects local storage, not server storage. But it can free up space on your hard drive.

Upgrade Your Outlook Storage Plan

If cleaning doesn’t give you enough room, it’s time to buy more storage. Here are your options.

Microsoft 365 Basic Or Personal Plans

Microsoft 365 Basic gives you 100 GB of mailbox storage for about $1.99 per month. The Personal plan includes 1 TB of OneDrive storage, but your mailbox stays at 50 GB (for Outlook.com) or 100 GB (for Exchange). Check your plan details:

  • Outlook.com free: 15 GB mailbox storage.
  • Microsoft 365 Basic: 100 GB mailbox storage.
  • Microsoft 365 Personal: 100 GB mailbox storage (plus 1 TB OneDrive).
  • Microsoft 365 Family: 100 GB per user (up to 6 users).

To upgrade, go to your Microsoft account page, select “Subscriptions,” and choose a plan. Payment is monthly or yearly.

OneDrive Storage For Attachments

You can also store attachments in OneDrive instead of in emails. When you attach a file in Outlook, choose “Upload to OneDrive” instead of “Attach as copy.” This saves space because the email only contains a link, not the file itself. Your OneDrive storage is separate from your mailbox.

If you have a Microsoft 365 plan, you get 1 TB of OneDrive space. Use it wisely.

Third-Party Email Archiving Services

Some services like Mimecast or Barracuda offer cloud archiving. They store old emails externally, so your Outlook mailbox stays small. These are usually for businesses, but individuals can use them too. Costs vary.

Advanced Tips For Power Users

These methods require a bit more effort but can save you a lot of space.

Use Outlook Rules To Auto-Delete Or Move Emails

Set up rules to automatically delete or move emails from certain senders. For example:

  • Move newsletters to a separate folder.
  • Delete emails from mailing lists after 30 days.
  • Forward large attachments to OneDrive and delete the original.

Go to File > Manage Rules & Alerts. Create a rule with conditions like “from a specific sender” or “with attachments larger than 5 MB.”

Compress Your PST File

If you use a POP or IMAP account, your emails are stored in a PST file. Over time, this file can become bloated. To compress it:

  1. Close Outlook.
  2. Go to Control Panel > Mail > Data Files.
  3. Select your PST file and click “Settings.”
  4. Click “Compact Now.”

This can shrink the file size by 20–40%.

Export And Delete Old Emails

Export emails to a PST file, then delete them from the server. In Outlook desktop:

  1. Go to File > Open & Export > Import/Export.
  2. Choose “Export to a file” and select “Outlook Data File (.pst).”
  3. Select the folder you want to export (e.g., Inbox).
  4. Save the file to your computer.
  5. After export, delete the emails from Outlook.

This is great for archiving emails you rarely need.

Use The “Online Archive” Feature (Exchange Only)

If you have a Microsoft 365 Business or Enterprise plan, you get an “Online Archive” mailbox. It’s automatic and moves old emails to a separate folder. To enable it:

  1. Go to File > Info > Tools.
  2. Select “Manage Online Archive.”
  3. Choose “Enable Online Archive.”

Emails older than 2 years are moved automatically. You can access them in the left pane under “Online Archive.”

Common Mistakes To Avoid

When trying to free up space, people often make these errors:

  • Deleting emails without emptying the Deleted Items folder. They still take up space.
  • Forgetting about the Sent Items folder. It can be huge.
  • Not checking the RSS Feeds folder. If you subscribe to RSS, they can fill up fast.
  • Ignoring the Calendar and Tasks folders. They also count toward storage.

Always check all folders before assuming you’ve cleaned enough.

How To Monitor Your Outlook Storage

Keep an eye on your usage to avoid surprises. Here’s how:

  • In Outlook.com: Click the gear icon > View all Outlook settings > General > Storage.
  • In Outlook desktop: Go to File > Info > Mailbox Settings > Mailbox Cleanup > View mailbox size.
  • In Microsoft 365 admin center: Go to Users > Active users > select a user > Mail tab > Mailbox usage.

Set a reminder to check every 3 months. This helps you stay ahead of the limit.

Frequently Asked Questions

How Can I Add More Storage To Outlook Email For Free?

You can free up space by deleting large attachments, emptying Deleted Items, and archiving old emails. These methods don’t cost anything. You can also use OneDrive for attachments to avoid using mailbox storage.

What Is The Maximum Storage For Outlook Email?

Outlook.com free accounts have 15 GB. Microsoft 365 Basic gives 100 GB. Business plans can go up to 100 GB per user, with an option for unlimited archive storage.

Does Deleting Emails In Outlook Free Up Space Immediately?

Not always. You must empty the Deleted Items folder. Also, it can take a few minutes for the server to update. If you use a desktop app, you may need to send/receive to sync.

Can I Increase Outlook Storage Without Upgrading My Plan?

Yes, by using the cleanup methods above. Archiving, deleting attachments, and using OneDrive links can free up significant space. You don’t have to pay if you have room to clean.

What Happens If My Outlook Mailbox Is Full?

You won’t be able to send or receive new emails. You’ll get a warning message. You can still access old emails, but new ones will bounce back. You need to free up space or upgrade.

Final Thoughts On Managing Outlook Storage

Running out of space is annoying, but it’s fixable. Start with the free methods—clean attachments, empty folders, archive old emails. If that’s not enough, consider upgrading to Microsoft 365 Basic or using OneDrive. The key is to stay proactive. Set a monthly reminder to check your storage and delete what you don’t need.

By following this guide on how to add more storage to Outlook email, you’ll never see that “almost full” message again. Your inbox will stay lean, and you’ll have room for what matters. Remember, a clean mailbox is a happy mailbox.