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  1. #1
    Just Joined!
    Join Date
    Mar 2003

    sendmail and exchange

    hi all i have Microsoft exchange server (mail server) now i want to add a
    sendmail server in my setup also. Can anyone tell me whether they can co exist or not. Is it possible to export all my users in exchange to sendmail server i have to use ldap.......plz tell me where can i find suitable documentation on implementing sendmail in windows environment

    thanks in advance

  2. #2
    Linux Guru
    Join Date
    Oct 2001
    Täby, Sweden
    I'm not sure exactly what it is that you want to do. Do you want to run sendmail under Windows? In that case, I really don't think many can help you here, but I don't know. If you want to add a Linux/UNIX server in an otherwise Windows-dominated network, could you please describe your current setup more thoroughly and describe how you want it to look in the end?

  3. #3
    Just Joined!
    Join Date
    Jun 2003
    Dunblane, Scotland
    The questions are difficult to answer helpfully because Exchange and sendmail are actually very different beasts.

    The quick answers are: Yes; Not easily that I know of; LDAP is the best, but not the only, solution; O’Reilly may have a book on it. Now for the slow, but hopefully more helpful answers.

    It appears that you have misjudged the capabilities of sendmail. It is primarily a mail transport agent (MTA) that implements SMTP (Simple Mail Transfer protocol).

    So, assuming a sendmail server, when a user sends an e-mail from Outlook, Evolution, Kmail or whatever, the e-mail program talks to sendmail using SMTP. Sendmail then runs a whole load of filters / header re-writing rules before doing essentially, one of two things: 1) It forwards the message onto another server (probably also running sendmail) via SMTP and lets it worry about it; or 2) It delivers the mail to a locally stored mailbox.

    These mailboxes have nothing to do with sendmail and it is possible to run sendmail without them, and it is possible to use the local mailboxes without using sendmail (there are other MTA’s out there).

    To gain access to the mailboxes another protocol is commonly used called POP3 (for Post Office Protocol version 3). (There is another gaining favour called IMAP – Internet Mail Access Protocol). This provides the ability to get a list of messages in the mailbox and to “download” the messages onto your local mail client.

    To provide address book functionality to your users you could set up an LDAP server, which provides remote queriable access to a hierarchical database. Essentially you can connect to an LDAP server and run a query like “give me the e-mail address of all users that have a surname starting with b”. A good e-mail program will be able to talk to an LDAP server.

    Exchange is, in effect, a combination of sendmail (for SMTP) + pop3d (for pop3) + slapd (for LDAP). Although Active Directory may be used for the LDAP bit – I forget.

    If you want to run everything on the same box, you might find it difficult. If Exchange is configured as an SMTP server then it will conflict with sendmail over the SMTP port (port 25). It may also conflict with slapd over the LDAP port (port 389). I don’t think Exchange supports pop3 – at least not out of the box.

    If you wanted to put a sendmail/pop3d/slapd server in your windows network then it wouldn’t upset Exchange, nor would it upset sendmail – but I can’t see why you would want to do this.

    The cheapest way of implementing an Exchange-like system (without the shared folders or tasks or calendaring stuff) is to install linux, configure sendmail. Create users for each person you want e-mail for (but remember to disable interactive logons). Create a database with all the e-mail and contact information and connect slapd to it (for LDAP). You may also have to configure DNS so that mail is routed correctly. Essentially all of these come in a standard linux distribution, so you wouldn’t have to pay anything extra, or any user based licence fees.

    It’s also not a easy way of doing it. Sendmail and bind (for DNS) are not easy to configure. Slapd is not trivial either. There’s no automatic way of exporting exchange users then creating pop3 accounts for them (although I could probably knock together a script in a couple of days). I can guarantee that if you don’t know anything about sendmail / bind / slapd now, it would take months from a standing start to get a fully working and reliable system.

    It is, however, an excellent introduction into networks / linux / administration. But not for the faint-hearted. O’Reilly do some good books on all the tools that you’re likely to need for it.

    Sorry for the length of the post!


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