The IMail Server IMAP4 Implementation

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The IMAP4 Server lets any IMAP4 mail client communicate with IMail Server. Supported IMAP4 clients include Netscape Communicator and Internet Explorer 4.0 and above. Many mail client vendors are adding IMAP4 support.

As a Windows NT service, the IMAP4 service can run completely hidden or with some feedback. The IMAP4 server continues to run when you log off the Windows NT system.

IMAP4 Server Support

IMAP4 handles mail access only, and relies on SMTP for sending and receiving mail over the Internet. The IMAP4 server allows an IMAP4 client to do the following:

• Access remote mailboxes as if they were local
• Read mail from more than one computer because mail is stored on the server system
• Access mail offline or online. Offline/online access behavior is determined by the mail client that is used.

  Offline access means that the mail client connects to the IMAP4 server, downloads the message headers, then disconnects.

  • If the user reads a message that has not been previously downloaded, the mail client re-establishes the connection and downloads the message.
  • If the user chooses to read a message that has previously been downloaded, the mail client shows a local copy.

Online operation is the same as offline, except that an open connection is maintained between the client and the server.

The mail client may support switching between IMAP4 and POP3 methods, both of which are supported by IMail Server.

Full IMAP4 Client Support

The IMAP4 client can access remote message stores (on the mail server) as if they were local. Users can:

• View message headers before downloading
• Select a message or part of a message for downloading
• Leave messages on the server for archiving and sharing
• Send and receive MIME-based attachments
• Manipulate remote mailboxes other than the MAIN
  (or INBOX) mailbox

Mailbox Management

When a user creates a mailbox using an IMAP4 client, the mailbox is created on the IMail Server system. Because the IMail server will permanently store IMAP4 users' mail, you will want to configure the server with appropriate disk space and you will want to manage the disk space by monitoring mailbox disk usage. As a general rule, a user should have four times the amount of free disk space as their entire users directory takes up.

With IMAP4 user accounts, the system administrator can:

• View, delete, or rename the mailbox directories;
• Set maximum mailbox size and maximum number of messages for each user or globally
• Delete old messages by specifying a date or number of days for which messages older than the date will be deleted.

For information on maintaining user mailboxes, see "Working with User Mail Accounts".

Administrators can also set an option that determines whether users must subscribe to a private mailbox before they can read it. For more information, see "Configuring the IMAP4 Server".

Public Mailboxes

The IMAP4 server provides a means of creating a public mailbox in which you can post messages for reading by IMAP4 clients. To create a public mailbox, create a user ID named public. Any mailboxes in the public directory will be available for reading by IMAP4 clients.

Administrators can use the public user ID to post messages. Users other than public can only read the public mailboxes. Administrators can set an option that determines whether users must subscribe to a public mailbox before they can read it.

Public mailboxes are read-only by design, and only the user public can administer the public mailboxes. Messages received for this account and its sub-mailboxes are treated as normal, but users other than public who access these mailboxes through IMAP4 have read-only permissions. If a user tries to mark a message in a public folder as read, he will be notified that the mailbox is read-only.

Ipswitch, Inc. http://www.ipswitch.com

©Ipswitch 2001 IMail Server Support Center