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Joe St Sauver, Ph.D.
Director, User Services and Network Applications
joe@uoregon.edu
While this traditional format is simple, efficient in its use of disk storage, and broadly supported, it slows down and generates unnecessary input/output (I/O) as the size of the mailbox increases. For example, deleting a single mail message from the middle of a traditional mailbox requires that the entire mailbox be rewritten, potentially generating hundreds of megabytes worth of I/O. There are a number of alternative mailbox formats, each with its own strengths and limitations.
One of those alternative formats, (the format we'll be moving to) is called "maildir."[1] This format stores each message as a separate file, instead of storing dozens (or hundreds or thousands) of messages in a single mailbox file. It is true that maildir is slightly less efficient in utilizing disk space (even a one-word email message takes up a minimum of 8KB on our filer), but mail access and manipulation tends to be far more nimble.
Moreover, because each message is stored in a separate file, a mail user agent (MUA) can read and delete messages while new mail is being delivered without the need for complex file-locking gyrations.
As a first step toward moving uoregon.edu accounts to maildir format, and because UW IMAPd does not have native maildir support, we've replaced UW IMAPd [2] with Dovecot. [3] Overall, it's been a smooth transition for UO users.
Later this summer, our systems staff will convert user mailboxes from the traditional format to the new format—again, a step that should not be noticeable to most UO mail users. This article is simply meant to alert you to the fact that this change will be taking place this summer.
Q. I'm a UO web email user. Do I need to do anything as a result
of this change?
A. Web email will continue to work as usual and
you don't need to do anything as part of this change.
Q. I use an IMAP or POP client (such as Mozilla Thunderbird, Eudora, or Outlook
or Outlook Express). Do I need to do anything as a result of this change?
A. IMAP and POP also will continue to work as usual, and you do not need
to make any changes.
Q. I use a command line email program such as Pine at the % prompt. What
about me?
A. We will centrally reconfigure Pine for all users so it accesses
uoregon.edu mail through IMAP. Pine should work as it normally does, except you'll
be prompted to log in with your uoregon.edu username and password when you start
Pine. If you use a command line email program at the % other than Pine, please
email consult@uoregon.edu so we can discuss the potential impact of this conversion
on the mail program you use. (Some command line email programs support maildir,
and some do not).
Q. I forward my mail to another account. Does this change impact my ability
to do that?
A. No. You will continue to be able to forward your mail to another account.
Q. You mentioned that maildir is less efficient in terms of the amount of
disk space it uses. I'm close to using all my disk space now. When you convert
to the new format will I go over my quota?
A. We will be increasing user disk quotas at the time of the maildir conversion
to make sure the new format doesn't push anyone over quota.
Q. What's the exact date of the mailbox format conversion?
A. That date is still being determined at press time; we will provide further
scheduling information as we get closer to the conversion date. Information
will be posted to the deptcomp and sys-status listservs, as well as to the
shell.uoregon.edu message of the day and the web page at http://status.uoregon.edu/
Q. I have a question you haven't covered. Who can I talk to about that? A. If you have any questions about the conversion to maildir format, please email consult@uoregon.edu or call 346-1758. UO faculty, students, and staff should also feel free to contact me directly (joe@uoregon.edu or 346-1720).
[1] http://cr.yp.to/proto/maildir.html
[2] http://www.washington.edu/imap/
[3] http://www.dovecot.org/