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Mail quotas on the SCS Exchange server

SCS Facilities provides a Microsoft Exchange Installation, exchange.cs.cmu.edu, for use by the SCS community. To take full advantage of the Exchange System, users are encouraged to store all of their e-mail messages on the server, which arrangement allows access to mail from any IMAP or MAPI (Outlook) client. As with any shared resource, unfortunately, comes the possiblity that a particular user may (either intentionally or unintentionally) impact other users. In the case of the Exchange Mail system, one user may receive enough mail to fill a disk partition, which would prevent all users of that partition from receiving e-mail. In addition, some E-mail clients have a finite limit on local storage that can affect synchronization of offline folders (OST), such as Microsoft Outlook.

In order to minimize potential problems, SCS Computing Facilities implements on our Exchange e-mail System a quota system that limits the amount of disk space any particular user can utilize. This document outlines how the quota system is implemented, how users can recognize when they approach or exceed their quota, and how to remedy that latter situation.

Quota Implementation

A disk quota limits the amount of mail that you can store on the Exchange Mail system server. Mail quotas are different from (and do not count towards) your AFS disk quota, or any quota that may exist on another system you may log into. Clients such as Outlook are limited to a two Gigabyte (2GB) maximum size for the Offline folder store (OST) and local Personal (PST) store files. Therefore, the normal quota for the Exchange Mail System is two gigabytes per user.

Am I subject to the quota?

If you receive email via the Exchange Mail System (that is, your mail is forwarded to either "e2k.srv.cs.cmu.edu" or "exchange.cs.cmu.edu," then you are subject to the quota. However, it is important to note that, under certain conditions, your mail may not be stored on the server. If you use an IMAP or MAPI capable client (such as Outlook, Mozilla, or the Outlook Web Access client) then your mail is most likely stored in the Exchange System. If you use a POP client (such as MH, Pine, Outlook configured for POP mode) that downloads your mail to your local system, then your mail may not be stored on the server, and you may not be affected by the quota, though local storage issues described above may still apply. If you are unsure, contact the SCS HelpDesk, <help+@cs.cmu.edu> or x8-4231, for assistance.

Another possibility is that your mail is being sent to the SCS Corvid mail system maintained by SCS Computing Facilities. If your mail is forwarded to "imap-ns.srv.cs.cmu.edu" or "imap.srv.cs.cmu.edu," please review our page describing IMAP quotas as implemented in the SCS environment.

What if I need more than 2 gigabytes of space?

It is important to note that the e-mail quotas are not intended to limit the amount of legitimate mail that you store on the Exchnage Mail System - quotas are designed to limit the impact that a single user can have on other users and technical limitations of the Outlook client. If you currently have more than two gigabytes of e-mail stored in the Exchange Mail System, you are encouraged to contact SCS Computing Facilities (help@cs.cmu.edu) for assistance in archiving items or configuring local folders in Outlook to store offline items.

Recognizing when you are near or over quota

The Exchange Mail System enforces two different quotas for user e-mail:
  • a "soft" quota, reached at 90% of your listed quota (1.8 gigabytes per user). When this quota is reached, you will begin receiving notification (via E-mail) that you are nearing the quota limit. When you reach this threshold, you can still send and receive new mail into your Exchange mailbox.
  • a "hard" quota, which is normally 2 gigabytes. When this quota is reached, you will not be able to send any new mail through the Exchange syst until you reduce your disk usage below your quota.
When you reach your "soft" quota, the Exchange System will begin informing your e-mail client that your mailbox is near its quota. How your e-mail client displays this warning depends on the particular client you are using. Some common clients are listed below, along with how they notify users.

Remedying the Over-Quota Condition

In order to fix the over-quota condition, you should remove mail from the Exchange System. To do this, you have several options:

  • Empty your trash or deleted items folder. Most e-mail clients have a "trash" or "deleted items" folder where deleted e-mail messages are stored. You should be able to empty this folder through your e-mail clients interface. For example, under Netscape/Mozilla, you can select the "Empty Trash" item under the "File" menu. You should review the contents of your trash folder to make sure that there are no messages that you want to keep and move them to a non-system folder.
  • Compact  your folders. In some cases, when you delete an e-mail message, it is not moved to the "trash" folder, but is simply marked as being deleted. In this case, the message is still on the server until you "compact" your folders. You can compact your folders through your e-mail client interface. For example, in Netscape/Mozilla, you can select "Compact Folders" from the "File" menu.
  • Delete SPAM messages. If you are set up to use the anti-SPAM service, messages that are identified as SPAM are refiled automatically into a folder under your INBOX. This folder is often named "SPAM" or "Junk". You should review the contents of these folders periodically and delete messages that are clearly SPAM.
  • Delete messages you no longer need, especially from your "Sent" folder. Most e-mail clients automatically file a copy of outgoing messages under the "Sent" folder. You should review the contents of this folder periodically to weed out messages that you do not need.
In deleting messages, you should pay special attention to messages that may have large attachments. These can take up a large amount of disk storage on the Exchange System - if you do not need the message (and attachment) any more, you should delete these messages if possible. The attachment can aslo be save on the local filesystem or in your AFS home directory.