How to Increase Outlook Mailbox Size: A Step-by-Step Guide

Running out of space in your Outlook mailbox can be a real hassle, especially when you’re in the middle of important work. Luckily, there are a few simple steps you can take to increase the size of your mailbox and get back to business as usual.

Step by Step Tutorial: How to Increase Outlook Mailbox Size

Before we dive into the nitty-gritty, let’s talk about what we’re trying to accomplish here. By following these steps, you’ll be increasing the storage capacity of your mailbox, so you can keep more emails, calendar items, and attachments without running into annoying “mailbox full” notifications.

Step 1: Check Your Current Mailbox Size

Before you do anything, you need to know how much space you’re currently working with.

In Outlook, you can easily check your mailbox size by navigating to the “File” tab, then clicking on “Tools” and selecting “Mailbox Cleanup.” From there, you can view the total size of your mailbox. This step is crucial because it gives you a baseline to work from.

Step 2: Archive Old Emails

Now that you know your current size, start archiving old emails to free up space.

Archiving is like moving your old emails to a storage unit – they’re still there if you need them, but they’re not taking up valuable space in your main mailbox. To archive emails, simply right-click on the folder you want to archive (like your Inbox), select “Properties,” then click on “AutoArchive” and choose your settings.

Step 3: Empty Your Deleted Items Folder

Deleting emails doesn’t actually free up space until you clear the Deleted Items folder.

Think of your Deleted Items folder as a trash can – it’s where your emails go when you delete them, but they’re not gone for good until you take out the trash. To empty this folder, simply right-click on the “Deleted Items” folder and select “Empty Folder.”

Step 4: Compact Your Mailbox

Compacting your mailbox is like squeezing the air out of a packed suitcase to make more room.

In Outlook, you can compact your mailbox by going to “File” > “Account Settings” > “Account Settings,” then double-clicking on your email account. Under the “Data Files” tab, select your data file and click on “Settings,” then “Advanced” and “Outlook Data File Settings.” From there, you can click “Compact Now.”

Step 5: Increase Your Mailbox Size Limit

If you’re an admin, you can increase the size limit of mailboxes for your users.

This step is a bit more technical and might require administrator access. If you have the proper permissions, you can increase the mailbox size limit by using Exchange Management Shell commands or by adjusting settings in the Exchange Admin Center.

After completing these steps, you should have a significantly larger mailbox size, allowing you to store more emails and attachments without worry.

Tips: How to Effectively Increase Outlook Mailbox Size

  • Regularly archive emails that you no longer need immediate access to.
  • Set up auto-archiving to automatically move older emails to your archive folder.
  • Unsubscribe from newsletters or promotional emails that you no longer read to prevent unnecessary clutter.
  • Consider using a third-party email cleanup tool to help manage your mailbox size more efficiently.
  • Always double-check before permanently deleting any important emails while cleaning up your mailbox.

Frequently Asked Questions

What is archiving in Outlook?

Archiving in Outlook refers to the process of moving older items from the main mailbox to an archive folder, which helps to free up space while still keeping the items accessible if needed.

How often should I compact my Outlook mailbox?

It’s a good idea to compact your Outlook mailbox periodically, such as every few months, depending on how frequently you use email and how quickly your mailbox fills up.

Can I increase my mailbox size on a free Outlook account?

The mailbox size limit for free Outlook accounts is set by Microsoft, and users cannot increase it. However, you can manage your mailbox effectively to stay within the limit.

Will increasing my mailbox size slow down Outlook?

Not necessarily. As long as you keep your mailbox well-organized and don’t exceed your computer’s capacity, a larger mailbox shouldn’t slow down Outlook significantly.

What should I do if I don’t have admin access to increase the mailbox size limit?

If you don’t have admin access, focus on steps 1-4 to manage your mailbox size. You can also contact your admin or IT department for assistance.


  1. Check your current mailbox size.
  2. Archive old emails.
  3. Empty your Deleted Items folder.
  4. Compact your mailbox.
  5. Increase your mailbox size limit (if you have admin access).


Congratulations on taking the initiative to increase your Outlook mailbox size! With the steps outlined in this article, you’re now equipped with the knowledge to manage your mailbox effectively, ensuring you have all the space you need for your important emails and attachments. Remember to routinely check and clean your mailbox to keep it from getting too full again. And don’t forget, if you ever hit a snag or aren’t sure about something, it’s okay to reach out to a more tech-savvy friend or your IT department for a little help. So, take a deep breath, roll up your sleeves, and get your Outlook mailbox in tip-top shape. Your future self will thank you for it!

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