IMAP And POP Mailers Make E-Mail Easy
By Greg Yerxa
As simple as sending an e-mail message may seem to be, there are serious issues like usability, feature sets and protocols to consider when selecting an e-mail client for your organization. If you're not using a proprietary e-mail system like Lotus Notes or Microsoft Exchange, you've got many options before you, including HTML support for administration and
messaging. In this Buyer's Guide, we'll discuss the relative merits of the Internet Mail Access Protocol (IMAP) and Post Office Protocol (POP) standards, and introduce the most critical features for the next generation of e-mail clients.
Do IMAP or Do I POP?
In choosing an e-mail client, you must consider not only its general overall functionality but also the server-side organization of your messag
ing system, which may limit your choices. One of the first considerations regards your system's use of IMAP and/or POP.
IMAP is fast becoming the preferred e-m
ail protocol, primarily because of its server-side mail management features. In comparison to the incumbent POP, IMAP offers many more capabilities. However, they come at the expense of heavier demand on your server. If you've got the back-end horsepower for it, IMAP can save your users a lot of work and increase the speed of e-mail communications drastically.
Among IMAP's features are selective downloading, server-side folder hierarchies, shared mail and mailbox synchronization. Frequent travelers should demand IMAP clients because IMAP will let them selectively fetch individual message parts or the structure of a message without downloading it. The protocol also lets clients utilize the server for message searches, minimizing the data transferred over the network. For example, let's say you check your mail while in the field via a 14.4-Kbps con
nection and find that you've received a 5-MB ZIP file from headquarters. With an IMAP mailer, you can download everything except the attachment. Although some POP mailers let you skip messages that are larger than a predefined limit, IMAP mailers handle them much more gracefully. By downloading only the headers at first, IMAP lets you determine what to read and when.
POP and IMAP both utilize a drop-and-store method for mail delivery: The server constantly accepts incoming mail and "drops" it into mailboxes on the server. A message is "stored" on the server until a client moves or deletes it. With a POP client, you must download the mail from the server immediately because POP mailers don't handle server storage of messages very well. If you have an IMAP client, however, you can maintain a folder hierarchy on the mail server or in a user account, depending on the installation of the IMAP server. The advantages of a server-side hierarchy of folders are twofold: Your messages are not only centrally located f
or easy access from multiple locations, but also not automatically transferred across the network. Additionally, multiple folders can be created, deleted or renamed
on an IMAP server, but not on a POP server.
Of course, if your company e-mail server or Internet service provider (ISP) doesn't support IMAP, you won't be able to use an IMAP client. Fortunately, many clients support POP and use IMAP as a second protocol.
Who's Who and What's Where?
Directory services probably are near the top of your list of message system requirements. In choosing an e-mail client, you must examine the directory services technology used. Many different protocols are available, including X.500, PH and Whois, and a host of proprietary directory protocols (see "Open Internet Standards Explained," at left). Your users may not be concerned about the method used as long as they get the results they want: information from the directory that they can use. The Lightweight Directory Access Protocol (LDAP) is the current
favored initiative in directory access protocols.
Netscape Communications Corp. and QUALCOMM are leading the pack with client software that supports LDAP. Other vendors have yet to realize the need for implementing extensive directory services in mail clients and excluding directory services other than a simple address book that you must maintain. Still others continue to use proprietary directory structures, hindering any possibility for growth from an intranet system to an Internet-based network. Look for clients that support more than one directory access protocol or whichever standard your server dictates your clients should have. For access to the widest range of directories, look for LDAP support in the client.
To download an Adobe Acrobat .pdf format version of the IMAP and POP Mailers Buyer's Guide charts, click here.
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