Email Server Upgrade

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Email Server Upgrade

• From UW to Cyrus

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What is an IMAP Server?

• Provides access to your mail messages stored on
  the mail server
• Requires authentication (login/password)
• Allow you to store and manage multiple mail
  folders on the mail server
• Can provide additional features (such as sharing
  mail folders) depending on the particular
  implementation
• Provides emulation of the POP3 protocol for
  backwards compatibility with older mail clients

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What an IMAP Server Isnt

• The IMAP server does not do the actual deliver of
  email messages to users
• Sendmail/Postfix/Qmail handles the delivery of
  email messages

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Message Stores

• A message store is the organization of how email
  messages are saved on the email server
• The mail deliver agent (sendmail/postfix) and the
  mail access agent (cyrus/uwimap) must agree on
  the same message store organization
• Also called mailstores

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UW IMAP Message Store

• University of Washington IMAP uses the Unix email
  message format, also known as mbox or Berkeley
  mail format
• Each mail folder is a file on the server and
  messages are stored in that file with a known
  message separator

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Cyrus IMAP Message Store

• Cyrus uses the maildir or a enhanced version of
  the maildir message store
• Each folder is a directory and each message is a
  separate file in the directory
• A lightweight database is used to speed access to
  the messages
• Cyrus was developed at Carnegie Mellon University

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UW IMAP Pros

• Simple to implement. No changes need to be made
  to message store format
• Can understand other message store formats other
  than Berkeley (Unix) mailbox format
• Can run on a machine that also allows users to
  login for interactive use (e.g. to use pine)
• Users or mail programs (mailx) can still access
  their mail files directly

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UW IMAP Cons

• Resource intensive. Entire mail folder must be
  read into memory and rewritten when changes are
  made. Doesnt scale well.
• Does not support IMAP Quotas. Must use Unix
  filesystem quotas.
• Does not support IMAP access control lists to
  allow others to share mail folders

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Cyrus Pros

• Uses an efficient, scalable message store
• Supports IMAP Quotas
• Supports IMAP Access Control Lists (ACL) to allow
  sharing of mail folders
• Has built-in server-side mail filtering language
  (Sieve)
• User accounts do not need to be tied to existing
  Unix accounts (you could use LDAP, or a separate
  account database).

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Cyrus Cons

• Requires the use of the maildir message store
• Designed to be run on standalone server that
  doesnt allow regular users to login to it
• Users no longer have direct access to their mail
  folders and messages. They must use the IMAP or
  POP3 protocol.
• Cant use familiar tools or config files
  (procmail, vacation and .forward files). The
  must use Sieve filtering language and other web
  developed interfaces.

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What are the Benefits to The College?

• Better Mail Quota Support
• Mailboxes dont get corrupt when user goes over
  quota which requires admin intervention on the
  current system.
• All mail folders including the INBOX are governed
  by the same disk quota (indirectly frees up space
  in their Unix account for more web pages/files).

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Benefits (continued)

• Collaboration Abilities
• Users can share mail folders with others on the
  system
• Users can setup dropbox mail folders that can
  be directly mailed into
• Bulletin Board (public access) folders can be
  created for announcements

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Upgrade Responsibilities for Current Mail Users

• Move current mail folders to new server (IT will
  convert their INBOX for them)
• Modify Netscape Preferences
• Learn/convert to new vacation feature
• Convert .forward contents to new system
• Redo server-side procmail filters to sieve
  filters if they current use it
• Optionally configure ACLs on mail folders

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Summary

• Cyrus is a modern IMAP server implementation that
  is feature rich, scales well and provides some
  collaboration capabilities