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Fix Mailbox Full

Fix Mailbox Full

By 21 November 2022July 27th, 2023Email

About Mailboxes

Everything that is stored in your inbox, your folders including the sent folder and trash is stored in a mailbox.  The mailbox is stored on your email provider’s server.  eg. If your using hotmail, your emails are kept on a Microsoft server, if your using gmail, your emails are stored on a Google server.  Every single email in your folders takes up file space within the server.

But generally, emails themselves dont take up much space, maybe just 1 to 2 kilobytes each, but file attachments takes up 10 times more space.  That’s because media files such as images and videos takes up far more space than text documents.  So when a mailbox is full, its usually because of huge amount of email attachments, not because of a huge amount of emails.

Email providers such as ourselves can increase your email storage limits to meet your requirements.

Duplicate Emails

If you have received a number of duplicate emails, which can happen in certain misconfigured email systems, you might just want to get rid of the duplicate emails first.  If you are using Outlook, there is a script here you can download which will search out duplicates and move them all in to a new ‘duplicate’ folder for you, after which, you can just delete the folder.

If you have a large amount of emails, this could up to 30 minutes to find them all.  A popup message will appear once its done.

Fix Outlook Storage size

Microsoft Outlook works by caching all your emails from the mailbox to your device, but Outlook has its own internal limit on how much it can handle.  The recommend size is around 20GB, but at around 50GB it will stop working completely and give the error:  ‘Outlook Data File has reached the Maximum Size’​.

This limit can be raised by adjusting a registry value within Windows, a script I’ve put together can do this for you quite easily, called ‘Outlook Store Increase’, which can also be found here.

You can raise it to quite high numbers, but don’t recommend it, anything above 80GB will usually results in file storage corruptions.

About Outlook Archive

If Outlook is full, or your mailbox is full, you can also use Outlook’s Archiving facility.  You can specify a date, and it will move the emails before that date in to a new ‘Archive’ folder.  The clever bit is that everything stored in that folder is stored in a new separate file on your device and not on the server.  So you still have easy access to your old emails, but they no longer causing you storage problems.

How to enable Outlook Archive

Create an archive file

  1. Outlook tool bar: Click ‘File’ > ‘Tools’ > ‘Cleanup Tools’ > ‘MailBox cleanup..’ > ‘AutoArchive’ button.

Set archive dates

  1. back to the inbox, and right click on ‘Inbox’ then select ‘Properties’
  2. select ‘AutoArchive’ tab, select to ‘Archive items in this folder using the default settings’
  3. click the ‘Default Achive Settings’ button and enable by ticking to run every 14 days.
  4. Change to clean out items older than 10 months

Set to archive sent folder

  1. right click on the sent items, and select ‘Properties’
  2. select ‘AutoArchive’ tab, and select to ‘Archive items in this folder using the default settings’

Set to archive other folders

  1. Repeat step 6 & 7 for other large folders

Create an archive file

  1. Outlook tool bar: Click ‘File’ > ‘Cleanup Tools’ > ‘MailBox cleanup..’ > ‘AutoArchive’ button.

Set archive dates

  1. back to the inbox, and right click on ‘Inbox’ then select ‘Properties’
  2. select ‘AutoArchive’ tab, select to ‘Archive items in this folder using the default settings’
  3. click the ‘Default Archive Settings’ button and enable by ticking to run every 14 days.
  4. Change to clean out items older than 10 months

Set to archive sent folder

  1. right click on the sent items, and select ‘Properties’
  2. select ‘AutoArchive’ tab, and select to ‘Archive items in this folder using the default settings’

Set to archive other folders

  1. Repeat step 6 & 7 for other large folders
    1. Make sure you can see the ‘On My Computer folder‘ in Outlook 2011. In Outlook 2011, click on the Outlook menu at the top of your screen, choose Preferences, then General. Uncheck the box that says Hide On My Computer folders. Now we are ready to get started.
    2. Right-click (or ctrl-click) the On My Computer heading (probably at the bottom of your folder list) and choose New Folder.
    3. Give your folder a name such as Archived Mail.
    4. Next, from the Tools menu select Rules.
    5. Under the On My Computer heading, select Exchange in the rules window, and click the “+” sign to add a new rule.
      ** Remember, rules are processed in order from top to bottom in the list. Use the arrows to adjust the rule order.
    6. Rule name: 300 Day Auto Archive, or whatever is suitable.
    7. When a new message arrives: define the criterion as “Date Received” + “is greater than or equal to” + “300” … days old
    8. Do the Following: define the action as “Move message” + “Archived Mail (On My Computer)”
      **Note: If you do not see the folder you wish to archive to, you will need to click on the drop down next to “Move Message” and select Choose Folder… then search for the archive folder. Under the folder name, the location “On My Computer” should be displayed.
    9. Finally, Click OK, making sure that the Enabled button is selected
    10. If you would like to apply this rule to your current mailbox, from the Message menu, select Rules, then select the rule you would like to process.
      **Note: This process may take some time to run initially, depending on how much mail you have in your Inbox. **Note: If you want to archive your entire mailbox, you will need to run this rule on each folder individually.

(NB: If the archived emails are important; once the archive have finished it is possible to locate the physical ‘archive.pst’ file they are stored in, and make a copy of the file; put it on the file server or something.)

Mail Attachment Sizes

Email attachments are generally known to have a limit of around 30MB (Megabytes), but when tested these limits we discovered what the actual numbers are and where the limits are applied: 

  • Our own standard hosting server has a limit of a 50MB (at 52,428,800 bytes) receiving and sending limit
  • Microsoft Outlook software is capable of handling 100MB attachments, but will stop you adding anything above 20MB (20,480,000 byte limit exactly), and say “The file you’ve attaching is bigger than the server allows”.    This isn’t necessary a server limitation, as the Outlook limit can be changed using regedit.
  • Outlook email server has a maximum limit of 50MB (49,283,072 bytes)
  • Windows Live Mail can handle 50MB but is limited to 10MB per sent email
  • Gmail says it can send 25MB and receive up to 50MB (their server states a 157,286,400 byte receive limit)
  • Ymail says it can send 25MB and receive 25MB (their server states a 41,943,040 byte receive limit)
  • Hotmail says is can send 10MB (server states a 49,283,072 byte maximum)
  • AOL says at 25MB send/receive limit (server states a 41,943,040 byte limit)
  • Protonmail says a 25MB send/receive limit (server states 36,480,000 byte limit)

Cloud storage services should be used to transfer large files, as email is generally not designed to handle large attachments by itself.

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