Managing IMAP

Chapter 4. IMAP Clients

Having an IMAP server is all fine and good, but it does you little good if you can’t actually read your mail. That, of course, is where the client comes in.

A microscopic examination of the strengths and weaknesses of each IMAP client on the market is somewhat beyond the scope of this book and beyond the capacity of a book publishing cycle, anyway. We’re currently on the threshold of an IMAP explosion in the Internet messaging industry. The features and bugs in any given IMAP client change with the phase of the moon. All that notwithstanding, here’s our version of a whirlwind tour of the best freely available (or at least freely demo-able) clients.

Client Features

This section begins by listing and describing a set of features that might be found in the ideal IMAP client. The features are cross-referenced with popular IMAP clients.

Features Reviewed

We cover Windows, Mac, and Unix clients separately; the results of the evaluations are shown in Table 4-1 . We looked for the following features in each of the clients. We reviewed only whether the feature exists and actually works or not—not how well it works.

Free

Is the client available completely free of charge?

LDAP

Does the client support remote directory lookups via LDAP?

ACAP

Does the client support storage and retrieval of client options via ACAP?

IMSP

Does the client support storage and retrieval of client options via IMSP?

NNTP

Does the client support reading Usenet news via NNTP?

MIME

Does the client handle MIME attachments? In other words, does a MIME attachment show up as a legitimate attachment with some indication of its MIME subtype (text/plain, application/postscript, or audio/basic, for example)?

SSL

Does the client support SSL IMAP sessions? This of course is only useful if you’ve built SSL support into your IMAP server.

Kerberos v4

Does the client support Kerberos authentication?

CRAM MD5

Does the client support CRAM message digests?

Disconnected

Does the client support disconnected mode? This item should be taken with a grain of salt. Some clients claim to support disconnected mode simply based on allowing a user to read mail while disconnected from the server. They do not, however, allow other basic actions (e.g., deleting messages) to be performed while the user is offline. In these cases, we gave the client a “no” on this point. The criteria that determine whether or not a client truly supports disconnected mode include:

• The user can read messages while disconnected from the IMAP server.

• Changes automatically synchronize when the user goes back online.

• The user can make changes, such as deleting messages or creating folders, while offline.

• The client keeps track of messages that have been replied to or forwarded when it goes offline.

Client-side filtering

Does the client support delivery of incoming mail to folders based on filtering parameters defined within the client?

Local address books

Can the client store email addresses locally?

Remote address books

Can the client store email addresses on a remote server?

Subscribe and unsubscribe

Can the client display or hide a folder by allowing the user to subscribe to or unsubscribe to the folder?

Nested folders

Can the client create folders within folders on the server?

Message threading

Can the client display messages by subject?

Shared folders

Is it possible for the client to create folders on the server and share them to other users, provided that the server supports shared folders?

ACL

Does the client include an ACL viewer and/or editor? This is primarily of interest to sites that use the Cyrus IMAP server.

Alerts

Does the client support RFC 2060–style ALERT response codes, which permit the system admins, through IMAP ALERTs, to notify system users of conditions liked planned outages or other changes in service condition?

Quota report tool

Does the client have a built-in mechanism for checking quota usage? This is primarily of interest to sites that use the Cyrus IMAP server.

Save outgoing mail

Is it possible to configure the client to save a copy of each outgoing message on the IMAP server automatically? Some clients save copies of outgoing messages only on the local machine.

Search on message header

Does the client support searching mail headers for a given text string?

Search on folder name

Does the client support searching for a folder name that matches a given text string?

Remote configuration storage

Can client configuration be stored on a remote server?

Table 4-1. Features Supported by IMAP Clients

Features	PINE4.21	StarMail5.1	OutlookExpress5.0	Netscape Messenger 4.61	Mulberry2.0	Eudora4.3
Windows	✓	✓	✓	✓	✓	✓
Macintosh	✗	✗	✓	✓	✓	✓
Unix	✓	✓	✓	✓	✗	✗
Free	✓	✓	✓	✓	✗	✓
LDAP	✓	✓	✓	✓	✓	✓
ACAP	✗	✗	✗	✗	✓	✓
IMSP	✗	✗	✗	✗	✓	✗
NNTP	✓	✓	✓	✓	✗	✗
MIME	✓	✓	✓	✓	✓	✓
SSL	✗[a]	✓	✓	✓	✗	✗
Kerberos v4	✓	✗	✗	✗	✓	✓
CRAM MD5	✓	✗	✗	✗	✓	✓
Disconnected	✗	✓	✓	✗	✓	✓
Client-side filtering	✓	✓	✓	✓	✓	✓
Local address books	✓	✓	✓	✓	✓	✓
Remote address books	✓	✓	✓	✓	✓	✓
Subscribe and unsubscribe mail folders	✗	✓	✓	✓	✓	✗
Nested folders	✓	✓	✓	✓	✓	✓
Message threading	✓	✓	✓	✓	✓	✓
Shared folders	✓	✗	✗	✗[b]	✓	✗
ACL	✗	✗	✗	✗[c]	✓	✗
Alerts	✓	✗	✓	✓	✓	✗
Quota report tool	✗	✗	✗	✗	✓	✗
Save outgoing mail	✓	✓	✗	✓	✓	✓
Search on message header	✓	✓	✓	✓	✓	✓
Search on folder/mailbox name	✓	✗	✗	✗	✓	✓
Remote configuration storage	✗[d]	✗	✗	✓	✓	✓
[a] SSL is supported in PC PINE only, but will be supported in PINE 4.30 for Unix. [b] Netscape Messenger allows users to share IMAP folders by setting ACLs on a per folder basis, but the ACL mechanism is proprietary and only works with Netscape’s mail server. [c] ACL viewer only. [d] Remote configuration storage will be supported in PINE 4.30.