How to Fix “Your Mailbox is Almost Full” – Expert Solution

Summary: Is Outlook constantly prompting the “Your mailbox is almost full” notification? Do you want to know why and how to fix it? If so, this blog is for you! Many Outlook users have told us that they often get this notification, even after deleting an email from their inbox. Therefore, in this blog, we will discuss how to fix this problem and stop receiving these notifications. Moreover, we recommend the best OST to PST Converter Tool to save your storage space since OST files take up more space than PST files. Before moving into the blog, let’s first understand why Your mailbox is almost full Outlook 365 messages.

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Reasons for the ‘Your Mailbox is Almost Full’ Notification

MS Outlook is one of the most widely used email clients for sending and receiving emails every day. This exchange of files and messages results in mailboxes becoming cluttered. Additionally, attachments attached to emails take up more space and cause errors. However, it is important to manage and organize mailboxes efficiently to keep your conversations running smoothly and avoid any performance issues. Furthermore, it’s important to figure out, what causes Your mailbox is almost full Outlook 365 errors:

• Oversized OST File: Typically, each Outlook profile is allocated a storage capacity of up to 50 GB, with some exceptional cases permitting even more. Once this space is full, it triggers the mailbox full error.
• Deleted Emails Occupying Space: Most of the time, users delete some unnecessary emails to declutter their inbox. However, deleted email also takes up a lot of space resulting in the ‘Your archive mailbox is almost full’ message.

Now the question arises, how to fix this error? So here are some solutions that can help you declutter Outlook 365 storage space and solve mailbox full issues.

Solutions to Resolve “Your Mailbox is Almost Full” Error

If you repeatedly receive Mailbox is Almost Full notification from the Outlook 365 team, you can consider the following strategies to resolve the problem and streamline performance:

• Use the Mailbox Cleanup tool to declutter your Outlook inbox
• Manually archive old emails to reduce the mailbox load
• Identify and delete oversized emails and associated attachments
• Delete all duplicate emails from your mailbox
• Empty the Deleted Items folder when Outlook restarts
• Deactivate the Cached Exchange Mode
• Save space by compressing the Outlook PST file
• Migrate attachments to OneDrive for more efficient storage
• Upgrade the plan and increase the Outlook data file limit, to accommodate more data.

Here, we’ll outline some key solutions that will make a big difference.

Outlook Mailbox Clean-Up Tool

You can declutter your mailbox by eliminating unnecessary emails and attachment files, using the Outlook Clean-Up Tool:

• Go to the File tab in Outlook.
• In the Info section, click on Tools.
• Choose the Mailbox Cleanup option.

• In the Mailbox Cleanup window, specify the number of days to search for items older than or the file size to identify items larger than.
• To permanently clear the Deleted Items folder, simply click on the Empty button.

Archive Older Emails

• Again, launch the Mailbox Cleanup Tool.
• In the Mailbox Cleanup window, click on the AutoArchive button

This will move all old items of Outlook to the archive folder of the PC. Further, you can locate these items in the Archive folder.

Delete all Oversized Emails and Attachments

Typically, large-sized emails and associated attachments occupy most of the Outlook mailbox storage space. Therefore, deleting such emails and attachment files may clutter up significant space. Follow the steps as follows:

• Open Outlook 365.
• In the Home tab, scroll down and click on Search Folders.
• Then, click on New Search Folder.

• Under the organizing mail, select the Large Mail option.
• Next, in the Customize Search Folder section, tap on Choose.
• Specify the mail size in the Show mail greater than the box.
• Click OK.

• Now, you can see all emails larger than the specified size in a new folder named “larger than size’.

It will automatically filter and collect all mail larger than the specified size. You can choose to delete those emails if you don’t need them.  

Deactivate Cached Exchange Mode

If Cached Exchange mode is activated in an Outlook 365 profile, it saves a local copy of the OST file on your PC. Additionally, if you are working with a shared mailbox and Cached Exchange Mode is on, it takes up a lot of space, hindering the performance of the email client. Consequently, to fix the ‘Your mailbox is almost full of Microsoft Exchange’ error, it is important to disable Cached Exchange mode:

• Open Outlook and access the File tab.
• Click on the Account Settings icon. 
• Again, from the drop-down choose Account Settings.

• Click to select the Microsoft or Exchange account from the list.
• Tap on the Change option.
• Click on More Settings. Move to the Advanced tab.
• Under the Microsoft Exchange window, uncheck the Use Cached Exchange Mode.
• Click OK and restart Outlook.

Empty the Deleted Items folder Automatically

You can auto-delete the deleted items folder by changing the settings of Outlook. Follow the steps, as follows:

• Open MS Outlook 365.
• In the File tab, click on Options.
• Go to the Advanced tab.
• Under Outlook Start and Exit, check the ‘Empty Deleted Item folders when exiting Outlook’ checkbox.
• Click OK.

Likewise, there are several ways you can stop receiving the “Your archive mailbox is almost full” notification. However, these methods are not as effective in dealing with full Outlook storage.

Limitations of the Manual Method

These suggested methods are only a partial solution to resolve this Outlook full error. There is only a chance that you can solve this issue by these measures. You cannot solely depend on these processes and you may lose your data. Furthermore, if you fail to solve this issue, you will have to move to the next one and then the next one. It will take you a long time to solve this issue. Therefore, we recommend a direct and dependable solution i.e. dedicated OST to PST Converter.

Best Approach for Resolving “Your Mailbox is Almost Full” Error

Here is why DRS OST to PST Converter is the best approach. Firstly, OST consumes larger storage than PST, and due to its large size, it’s susceptible to corruption. And PST files occupy less space compared to OST files. Therefore, converting OST to PST frees up plenty of storage space and also keeps your important data safe. 

Wondering if it’s easy and convenient to convert OST into PST? Yes, DRS OST to PST Converter is a secure and easy-to-use utility for converting any number of OST files to PST, at once. Apart from converting OST to PST, it allows users to migrate OST to other file formats and email clients. Moreover, you don’t need to worry about duplicate items in the resultant PST. Let us see how.

How to Convert OST to PST?

Resolve the “Your Mailbox is Almost Full” using DRS OST to PST converter. Follow the steps as guided below:

• Download the tool and run it as an administrator.
• By default, Single File/Multiple Files is selected. Click Next.
• Click on Select Files or Select Folders to add the desired OST file(s).
• Add OST file(s) from File Explorer and tap Next.
• Preview emails in the mailbox preview of the selected OST file. Click Next.
• Expand the Save/Backup/Migrate As field and select PST.
• Select other options/filters as per your requirements.
• Lastly, click on the Convert button.

Hence, this is how you can easily convert OST to PST and successfully resolve the ‘Your mailbox is almost full Outlook 365’ message issue. Apart from what is discussed above, the tool is embedded with various other latest features, for better user experience.

Conclusion

The error “Your Mailbox is Almost Full” may hinder Outlook’s performance and needs to be fixed as soon as possible. You can try various approaches discussed to fix this issue. Nevertheless, an expert-suggested method to deal with it is to convert OST to PST.

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