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Office of Information Technology

Reducing the Size of Your Mail Storage

Reducing the size of your mail file can have tremendous benefits for both you and AU's e-mail servers. You can dramatically improve the performance of your e-mail client by regularly: filing your e-mail messages into folders, archiving messages over a year old, and deleting large attachments. You will also help conserve storage resources and improve server reliability.

Checking the Size of Your Mail File

  • Lotus Notes users can click the FILE menu. Then, select APPLICATION and PROPERTIES. The Properties window will appear. Click the INFORMATION tab which is labeled with an i icon to see how much disk space your mail file uses and how many messages it contains.
  • AU WebMail users can check the size by clicking the PREFERENCES button. Then, click the ABOUT button from the Preferences window.
  • If you use an IMAP client (like Mac Mail, Mozilla Thunderbird, or Microsoft Outlook), you will need to log into AU WebMail through to check your file size in the Preferences window as described above.

Cleaning Out Your Inbox, Sent, and Trash Folders

  1. Locate and delete messages with the largest attachments:
    • You can easily find the largest attachments by sorting your e-mail by size. Click on the SIZE column in Lotus Notes to sort messages by size. This will work for most other e-mail clients as well. 
    • Locate the largest attachments. Then, either delete the messages or open each message and manually remove the attachments. To do this, right-click on the attachment. Select SAVE AND DELETE, if you want to keep the message in your mail file without the attachment. 
    • Don't forget to do the same for your other e-mail folders. 
    • When finished, you can click on the DATE column again to sort by date. Clicking twice on a column toggles between ascending and descending order.
  2. Empty your Trash and Junk Mail folders regularly:
    • Most e-mail clients automatically save copies of every message you send, so the SENT folder is often the largest folder. Follow the steps above to locate and delete large attachments that you have sent, but are also stored elsewhere. 
    • Empty your TRASH and JUNK MAIL folders on a regular basis. Within Lotus Notes, click the TRASH folder. Then, click the EMPTY TRASH button to delete all messages. Click the JUNK MAIL folder and click the DELETE ALL button.

  3. File your messages into folders to improve system performance:
    • You can sort your Inbox by the WHO column to quickly find all messages from a particular sender. 
    • Select multiple messages at a time by holding the SHIFT key (to select a range of messages) or the CTRL key (to select multiple individual messages). 
    • Drag the selected messages to the appropriate folder, or click the FOLDER button to select a folder to move the messages to. 
    • Lotus Notes will still allow you to search for a message in all folders by searching the ALL DOCUMENTS view.


A typical e-mail message without an attachment is only one or two kilobytes in size, but attachments can make an e-mail message much larger. When you reply to a message that contains an attachment, delete the original attachment from your response.

In Lotus Notes, select the WITHOUT ATTACHMENT options from either the REPLY or FORWARD buttons.

When someone sends you an attachment and you reply with a comment leaving the original attachment in the reply, you now have two copies of that attachment in your mail file. The original is in your Inbox and a copy is now in your Sent folder. If the recipient replies to you again with the same attachment, you will have three copies.

IMAP clients (like Mac Mail, Thunderbird, and Microsoft Outlook) generally do not include the original attachment in the reply by default.

Alternatives for Sharing Files

Some mail services reject messages that are over 5MB or 10MB. AU does not restrict attachment size internally, but it is something everyone should be aware of when sending messages, especially to off-campus recipients. Large attachments can quickly fill up mail files that have storage restrictions.

There are several other ways to share large files besides sending them as e-mail attachments, including:. 

  • AU faculty and staff can use their shared departmental drive (I:) to share files with colleagues within their department. 
  • You can copy a file into your G:\WWW folder and send someone a link to the file. 


If you would like assistance cleaning up your e-mail, please contact the IT Help Desk at 202-885-2550,, or AskAmericanUHelp.