Change in Way SSCC Inboxes Handled

We want to inform you of a new way e-mail stored in your Inbox folder will be handled. Each user's incoming messages (the Inbox) get stored on SSCC's mail server in a separate subdirectory of /usr/spool/mail. Under the new plan approved by the SSCC Steering Committee, when an Inbox exceeds 10 MB for over a week, the mail currently in the Inbox will automatically be moved to another mail folder in the user's home directory. The mail only gets moved -- no incoming mail is bounced and no mail gets deleted.

SSCC supports two protocols used by e-mail programs to access mail: POP (Post Office Protocol) and IMAP (Internet Message Access Protocol). If you are unfamiliar with these terms or do not know which protocol you are using, please read the last section of this article first.

This change only applies to those using SSCC mail accounts, though users of facstaff and students accounts are subject to the same problems caused by large Inboxes that motivated this new plan.

Why the change

The reason we are implementing a limit on the size of Inboxes is because the mail server's spool is getting too large. It currently contains over three gigabytes of messages. So, why not just buy more disk space? There are two main reasons: 1) mail server performance is affected by large mail spools. SSCC e-mail traffic has increased 30% over the past two years and industry experts predict that there will be a 40% annual increase for the next three years. SSCC would experience serious performance issues if the size of the mail spool continues to increase at its current rate. 2) large Inboxes account for a disproportionately large percentage of e-mail problems. These include problems resynchronizing Inboxes, mail programs timing out while checking for new messages, corrupted Inboxes that have to be restored, and slow performance when the mail program is loading. Smaller Inboxes make for better e-mail program performance.

Implementation dates

The majority of SSCC users already are using less than 10 MB for their Inbox and for them this change will have no effect. Users with Inboxes greater than 10 MB may want to spend time reducing the size of their Inboxes (although you don't have to) and in order to provide ample time for these users, we will be implementing the limit as follows:

You can check how much space your Inbox utilizes by typing "inboxsize" at the prompt from any of SSCC's UNIX computers.

Reducing the size of the Inbox

If you use IMAP, you can reduce the size of your Inbox by deleting the messages you no longer need and/or moving mail from your Inbox to another folder. When mail is transferred to another folder, it no longer takes up space in the mail spool. It is moved to your UNIX home directory.

If you use POP, make sure your e-mail program is not keeping copies of mail on the mail server or at least is only keeping copies for a brief period of time, preferably a week or less. Otherwise, even though you may delete a message (from your PC), a copy is still kept on the server. Not only does storing copies of mail on the server contribute to the bloated size of our mail spool, it also contributes to the e-mail problems mentioned above. You can check and/or change this option:

Note: You may be saving copies of your mail on the server and not even be aware of it. This is because when you check your mail using POP, only mail that has not been sent to your computer before is downloaded. A POP user never sees their entire Inbox unless they check from a different computer, or use an IMAP mailer such as MailSpinner. So, if you are a POP user, please follow the instructions above to check your configuration and change it if necessary.

How things will work after the change is implemented

Once the limit is in place, we will be sending system-generated messages warning users when they are approaching the limit. If a user exceeds the 10 MB limit for more than a week, the Inbox will be moved to the user's home directory into a new mail folder called Inbox_[date]. A message informing you of this transfer will be sent. For IMAP users, this folder will be accessible via the e-mail program just like any other folder once the mailbox list is "refreshed".

POP users shouldn't have problems with the size of their Inboxes unless they are keeping copies of their mail on the mail server for an extended period of time. But, if an Inbox gets moved to a user's home directory because of its size, the user will need to transfer the Inbox_[date] file to their mail directory on their PC before it will be accessible.

POP and IMAP protocols

SSCC supports two protocols used by e-mail programs to access mail: POP (Post Office Protocol) and IMAP (Internet Message Access Protocol).

E-mail programs configured to use POP, download all messages from the mail server to the user's PC hard drive when the user checks mail. POP works best when used with only a single computer, since it was designed to support "offline" message access, wherein messages are downloaded and then deleted from the mail server. POP is not compatible with access from multiple computers since it tends to sprinkle messages across all of the computers where the e-mail program is used.

IMAP is a newer protocol and stores Inbox messages on the mail server. This makes it easy to access mail from multiple locations. For example, e-mail stored on an IMAP server can be manipulated from a desktop computer at home, a workstation at the office, and a notebook computer while traveling, without the need to transfer messages or files back and forth between these computers. You can also use SSCC's web-based mailer, MailSpinner, if you are an IMAP user. IMAP also increases the security of your mail, as it is not available on your hard drive for anyone to read, and will still be intact and available to you even if something happens to your computer.

We encourage all users who are using POP to switch to IMAP. If you have switched from POP to IMAP in the past and switched back because you found IMAP slow, please reconsider IMAP. IMAP performance has improved significantly since replacing our mail server approximately two years ago. Contact Consultant and we will gladly make this change for you. If you are not sure which protocol you use, it's easy to find out:

SSCC staff want to make this a smooth transition and will gladly assist you in any way we can - contact Consultant (2-9917).

Nancy McDermott, Director
Social Science Computing Cooperative
University of Wisconsin - Madison
1180 Observatory Drive
Madison, WI 53706
(608) 262-3206