I am look into what LDAP is and how it works in regards to a Mail Client. My question is how does LDAP work? I understand that LDAP is:

A directory set of objects with attributes organized in a logical and hierarchical manner.

Does this mean that directory items are stored in a database or in some other fashion?

The real reason I ask my question is I have some general experience with Microsoft's Exchange server but am looking for and open source alternative. AKA looking for a tool that will use an IMAP or POP3 mail server and still allow you to link calendar, task and other information.

More Specifically I am looking for a good Linux Mail server that can do all the same types of things Exchange does.

  • Duffbeer - in your edit of his title, I don't think he wants Directory Services. He's just confused
    – Izzy
    Jul 17, 2009 at 20:20

6 Answers 6


LDAP has nothing to do with email. It's like comparing apples and oranges.


The Lightweight Directory Access Protocol, or LDAP (pronounced /ˈɛl dæp/), is an application protocol for querying and modifying directory services running over TCP/IP.1

A directory is a set of objects with attributes organized in a logical and hierarchical manner. A simple example is the telephone directory, which consists of a list of names (of either persons or organizations) organized alphabetically, with each name having an address and phone number associated with it.

See the Serverfault question "Is there any open source Exchange server?" for some really good answers to your real question, an open source alternative to Microsoft Exchange.


LDAP has precious little to do specifically with email. It is only a standard way of making a directory of users. There are tons of different LDAP directories. Microsoft's AD is one, the default variety used by exchange. SunONE is another.

LDAP is used for authentication mostly.

Here exchange-server-replacement-that-runs-on-linux is a pretty nice question about Linux based alternatives for Exchange. Which seems to be more what you are looking for.

Is there any open source Exchange server? ALso talks about it


LDAP is Light weight direcory protocal. It's basicly an application protocol for querying and modifying stuff.. It's not and email system at all. Sort of like MS Active Directory or novell directory services. Some mail servers authincate from an LDAP Server... some don't.

Directory items could be anything.. a user, organizations, individuals, and other resources such as files and devices, etc, etc...

so basicly the answer is no.. Ldap is not a capable of completing Exchange types of tasks.


GMail for Domains is free for <100 users, and where I frequently point SMB's that don't want the burden of Exchange.


If you're looking for a good Linux Mail Server and don't mind closed source products, Novell's GroupWise runs on Linux. Quite well from what I hear. It isn't free (far from) but does run on Linux, and does most of what Exchange does and all of the big stuff (shared tasks, shared calendars, shared resources, unified directory service, email). It even has Blackberry support, though it tends to lag Exchange by a year or two.


You should look at Zimbra, it has:

Check out LIVE DEMO

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