Exchange POP3 and ISA2k4 - Can receive mail over pop3 but can't send...

Posted on 2004-11-16
Last Modified: 2012-06-27
Hey Experts...

Just like the title an exchange server published behind ISA server, set up publishing rules for POP3...can connect and receive easily enough, but can't send...

sleepy, and out of ideas...

What do you guys (or gals) think?

Question by:neomage23
    LVL 4

    Expert Comment

    What error does it say?

    Another thing is when you telnet to interface of the ISA server where the Exchange using port 25 is published can you connect to it?
    LVL 20

    Expert Comment

    Where is your SMTP server defined ?
    Did you also published SMTP server using ISA publishing rule  ?

    follow the link below;en-us;287646&Product=exch2003
    LVL 6

    Author Comment


    I'm getting this error from an outlook express client:

    The message could not be sent because one of the recipients was rejected by the server. The rejected e-mail address was ''. Subject 'tset from cpser', Account: '', Server: '', Protocol: SMTP, Server Response: '550 5.7.1 Unable to relay for', Port: 25, Secure(SSL): No, Server Error: 550, Error Number: 0x800CCC79

    I can telnet to port 25 from within my office (LAN) and from a dedicated server that we have through a hosting company, but the odd thing is that I can't telnet to port 25 from my home ( cable inet). The above message is from the outlook express client on the dedicated server.


    SMTP seems to be working fine, I'm not getting any denied connection errors within the ISA logs. I used this guide to publish my exchange 2003 server....

    How should relaying be configured?

    LVL 20

    Accepted Solution

    to set the relay on exchange server

    1.Click Start, point to Programs, point to Microsoft Exchange, and then click System Manager.
    2. Expand Servers, expand <Server Name>, expand Protocols, and then expand SMTP.
    3. Right-click Default SMTP Virtual Server, and then click Properties.
    4 In Default SMTP Virtual Server Properties
    5.Under Relay restrictions, click Relay to verify relay restrictions.
    In Relay Restrictions, verify the following settings:
        Verify that the Only the list below button is selected. To list only those hosts you want to allow to relay mail, click Add, and then follow the instructions. If you click All except the list below, your server may appear to be a server that is a source of unsolicited e-mail on the Internet.
       Verify that the Allow all computers which successfully authenticate to relay, regardless of list above check box is selected. This setting allows you to deny access to all users who do not authenticate. Any remote POP and IMAP users accessing this server will authenticate to send mail. If you do not have users who access this server through POP or IMAP, you can clear this check box to prevent relaying entirely, thereby increasing security.
    LVL 6

    Author Comment


    it is set up that way...under Default SMTP Virtual Server Properties....Access....Relay Restrictions...

    The setting is set to "only the list below" ... the only domain that is granted is "" and there is a check next to "Allow all computers which success authenticate...."

    Ugh...I hate it when I can't figure things out.

    LVL 4

    Assisted Solution

    Ok have you setup your outlook express check "my SMTP needs authentication" what about your login name it should be, if ithat is the site of your Active directory if its mydomain.local then the login name in outlook express should be username@mydomain.local

    Hope this helps...

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