2 Ways to Fix Outlook Mailbox Full + 1 Tip to Protect Emails

Don’t know what causes Outlook mailbox full and how to solve this problem? Read this page and you will find the fixes, also a best backup software can help you protect your Outlook items from risk.


By Clytze Updated on March 2, 2023

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User case: Cannot send/receive mail your mailbox is full


I noticed this morning I was no longer receiving emails. When I looked closer it was my quota is full. I have spent the entire day deleting hundreds of emails and nothing changes. I use my email daily and this is unacceptable. Does anyone know what happened?

- Question from Microsoft Community

Microsoft offers 15 GB of email storage space per free Outlook.com account. Microsoft 365 subscribers get 50 GB of space. If all your emails are sent and received through your Outlook mailbox account, the storage space may start limiting the functionality when the number of emails you have reaches its maximum.

Outlook Mailbox Full

For example, you may get a warning when it reaches 90MB, you may not be able to send emails when it reaches 100MB, and you may not be able to receive emails when it reaches 110MB. This can be an unnecessary hassle for users who need to use email frequently to communicate back and forth.

Fortunately, this problem is solvable. Read the following sections and you will get simple solutions to get rid of it. Let’s check them together.

How to clean up Outlook mailbox full

Solution 1. Manage your mailbox full using Mailbox Cleanup tool

Cleaning your mailbox to manage mailbox size is a straightforward way to fix your archive mailbox is almost full. You can use Mailbox Cleanup option to check mailbox size, find/filter messages that are over a specific date or based on size, archive mail items, view deleted items folder size, and empty or delete deleted items and conflicting folders.

1. Navigate to File > Tools > Mailbox Cleanup.

Mailbox Cleanup

2. Once you’re in Mailbox Cleanup you will be able to:

  • View the total size of your mailbox and of individual folders within it.
  • Find items older than a certain date or larger than a certain size.
  • Archive items by using AutoArchive.
  • View the size of your Deleted Items folder and empty your Deleted Items folder.
  • View the size of your Conflicts folder and delete this folder.

Solution 2. Store attachments outside your mailbox

Saving attachments outside your mailbox to other places like OneDrive can help conserve mailbox storage and avoid Mailbox Full or Quota Exceeded messages. The steps are as follows:

1. Click Filter > Sort by and select Size.

Sort By

2. Open the message and then click Save to OneDrive option beneath the attachment.

3. Once the attachment is saved on OneDrive, delete the attachment permanently using Shift+DEL key.

By following these solutions, it is possible to prevent Outlook mailbox full after archiving and ensure that emails can be sent and received without any problems.

Protect Outlook data with best backup solution

For individual users or businesses, emails are extremely important and vulnerable to accidental deletion or corruption, thus causing huge losses. To ensure their security, it is recommended that you backup your Outlook emails and store them to a secure address.

Thus you’ll need a reliable email backup software AOMEI Backupper Professional to help you safeguard your Outlook data. You can save Outlook items to other safe destinations to prevent risks.

👣 You can backup Outlook mailbox to other paths including hard disks, USB drives, NAS devices, network locations, cloud, etc.
👣 By default, it supports you backup changed data only with Incremental Backup. You can also change to Differential Backup as well. Both of them can save a lot of time and space.
👣 In order not to forget to backup emails, you can set schedule backup at Daily, Weekly, Monthly and Event Trigger intervals.

Now, click the button below to download AOMEI Backupper Professional on your PC.

Download Free TrialWin11/10/8.1/8/7/XP
Secure Download

(This edition only supports Windows 11, 10, 8, 7, XP and Vista. For server users, try AOMEI Backupper Server.)

Follow the illustrated steps to complete Outlook mailbox backup with AOMEI Backupper:

Step 1. Open Outlook, type email address and click Connect, then follow the on-screen instructions to add the Outlook account.

Step 2. Once open it, click Backup and then Outlook Backup.

Outlook Backup

Step 3. Click Add Outlook data and select the Outlook items you want to backup. Then click OK.

Add Outlook Data

Step 4. Then click the box below to select a backup destination (here takes backup to cloud as example). Click Select a cloud drive and then select OneDrive/Dropbox/Google Drive you are currently using.

Select OneDrive

Step 5. Click Start Backup to backup Outlook to cloud immediately.

Backup Outlook to Cloud

  • You can click Backup Scheme to select clean old backups, thus you won’t be worry about too many backups take up your disk or cloud space, as well as space full issue.
  • Click Schedule Backup to set backup at Daily, Weekly, Monthly and Event Trigger intervals, thus you won’t forget to perform regular backup task.

Wrapping things up

Now you’ve got the practical Outlook mailbox full fixes after reading the whole guide. Since your Outlook mailbox emails are valuable, it is suggested to backup them and save them to hard drives or cloud services with AOMEI Backupper.

If you want to clone NVMe to larger NVMe with secure boot, AOMEI Backupper also provides you with Clone feature to finish the task without effort. Wanna explore more? Try it immediately!

Clytze · Editor
Clytze, an editor at AOMEI Technology, is passionate about safeguarding your digital world. She dedicates her expertise to empower users like you in data security and recovery. She firmly believes that everyone should have the tools and knowledge to protect their digital assets through computer backup, seamless disk cloning, and efficient file synchronization. Clytze is your trusted guide on the journey to data safety.