Outlook storage full: find out what is full, then fix it

When Outlook says your storage is full, first find out which storage is full. A free Outlook.com account (this includes Hotmail and Live.com addresses) has two limits: 15 GB for email, and 5 GB of Microsoft cloud storage that OneDrive and Outlook.com attachments share. A work or school account has a mailbox limit that your organization sets. When a free limit is reached, Outlook.com stops sending and receiving email. This page helps you find what is full and choose a fix. For the hands-on cleanup steps, read how to free up space in Hotmail and Outlook.com. For a short overview, see Outlook.com or Hotmail mailbox full.

What happens when Outlook storage is full

Microsoft describes three situations. All of them stop your email, so it is worth acting the same day.

• Your Outlook.com mailbox is full. You cannot send or receive email in Outlook.com. Emails that people send to you are returned to them. They must send the email again after you have space.
• Your Microsoft cloud storage is full. You also cannot send or receive email in Outlook.com, even when your mailbox still has room. Your OneDrive files become read-only, and new files do not upload or sync. Microsoft says that after 6 months it might delete your OneDrive and the files in it.
• Your work or school mailbox is full. You cannot send or receive messages, and people who email you get an error message that says your mailbox is full. Before that, Microsoft sends warning emails and in-app messages as the mailbox gets close to full.

Step 1: Find out what kind of account you have

The fix depends on who sets the limit. Use the table to find your row.

The Outlook app on your Mac, PC or phone usually shows the same mailbox as the website. If Outlook.com says the mailbox is full, the app says so too, and space you free in one place is freed everywhere.

Step 2: Mailbox or cloud storage?

On a personal account, the two limits fill up for different reasons. Your mailbox holds your emails, contacts and calendar. Your Microsoft cloud storage holds OneDrive files and photos, the OneDrive recycle bin, and, according to Microsoft, your Outlook.com attachments. So a OneDrive full of photos can stop your email, even if you never touch your inbox.

Microsoft's own help pages do not all describe this split in the same way. Do not guess. Look at both numbers before you delete anything.

The 5-minute checks

1. Check your email storage. Sign in to Outlook.com and select Settings > Account > Storage. You see how much space each folder uses.
2. Check your cloud storage. Sign in to your Microsoft account and open the Microsoft storage page. The What is Microsoft cloud storage? help page explains what counts toward it.
3. Look at Deleted Items. It counts against your storage until you empty it, or until each item is removed after 30 days.
4. Did you use Sweep? Emails removed with Sweep do not reduce your storage until they are also deleted from Deleted Items.
5. Look at Junk Email. Outlook.com deletes Junk Email items after 10 days, so this folder is rarely the problem.
6. Check the OneDrive recycle bin if cloud storage is the full one. It counts too.

The Storage page can also permanently delete all items in a folder, or only items older than 3, 6 or 12 months. That is fast, but it is permanent. Use it only on folders you do not need, or that you have already copied.

Your three options, in order

1. Clean up

Empty Deleted Items, delete newsletters you do not read, and find the largest emails with Filter > Sort by > Size. This is free and often enough when you are only a little over the limit. The full step list, with what to keep, is in free up space in Hotmail and Outlook.com.

2. Keep old mail on your computer, then delete it online

Most full mailboxes are full of old mail that you rarely open but do not want to lose. You can download a copy of that mail to your computer, check the copy, and then delete the mail from Outlook.com. The space comes back, and the mail is still there when you need it.

MailVault is a free desktop app for macOS, Windows and Linux that does this. It saves each email as a standard .eml file on your computer. With the free app you do it in two steps: Archive copies the mail into your vault, then Delete from Server removes it from Outlook.com. The one-step Archive & Delete, which checks each copy before it removes the server copy, is part of Premium. See how Archive & delete works.

3. Buy more storage

Microsoft 365 Basic, Personal and Family raise your email storage to 100 GB. The 100 GB mailbox is not part of a Microsoft 365 trial. Prices change by country, so check them on Microsoft's site. This is the right choice when you need every old email on your phone and on the web. It does not stop your mailbox from growing. We compare the two approaches in archiving locally vs paying for more storage.

When to pick which

• Mail is bouncing right now. Empty Deleted Items first. It is quick, and it removes only mail you already deleted. Then plan a longer fix this week.
• The mailbox is full of old mail. Archive it locally, then delete it from Outlook.com. This can free a lot of space without losing anything.
• Cloud storage is full, and OneDrive holds most of it. Deleting email helps only a little. Move or delete OneDrive files, empty the OneDrive recycle bin, or buy storage. Removing old emails with large attachments helps too.
• It is a work or school account. Ask your IT administrator first. Your organization may have an archive mailbox for you. Do not copy work mail to a personal tool if your company rules do not allow it.
• You need everything online. Buy storage, and accept that the bill continues.

If you choose to archive, make the copy first and delete second. Our guide to backing up Outlook.com email to a Mac compares the ways to make that copy, and freeing up email storage without losing old emails explains the same idea for any provider.

Notes for the Outlook desktop app

• Classic Outlook for Windows has File > Tools > Mailbox Cleanup. It shows the size of your mailbox and its folders, finds items older than a date or larger than a size, and empties Deleted Items.
• A .pst or .ost file lives on your PC. Microsoft documents a default size limit of 50 GB for these files. This limit is separate from your Outlook.com or work mailbox limit.

Frequently asked questions

What to do next

Run the 5-minute checks today, so mail stops bouncing. Then decide what to do with your old mail. If you want to keep it without paying for more online storage, MailVault keeps a copy on your own computer as plain .eml files, and the free app can archive and delete from the server in two steps. There is no MailVault account, and your mail does not pass through a MailVault server.

Sources: Microsoft Support, Storage limits in Outlook.com, Check email and cloud storage and Mailbox storage limits in Outlook (work or school accounts). Last checked: October 2026.