Can POP mail on my Exchange 2003 server but can’t send mail VIA SMTP

Had some users that had to be able to access the Exchange Server on their phone. Their phone doesn’t support push/pull and they insisted on POP and SMTP.  I warned them on the security issues regarding opening their server up to be an SMTP relay but they still wanted to proceed. 


I enabled POP3 and was able to download mail just fine.  My problem came with being able to send mail even though I had “SMTP server requires authentication.”  I tried from 4 different clients and was not able to send email.    I got numerous errors in my clients.  See below:

  1. The message could not be sent because one of the recipients was rejected by the server. ‘550 5.7.1 Unable to relay for, Port: 25, Secure(SSL): No, Server Error: 550, Error Number: 0x800CCC79
  2. Sending’ reported error (0x800CCC92) : ‘Your e-mail server rejected your login. Verify your user name and password in your account properties. Under Tools, click E-mail accounts.
  3. Task “” – Sending’ reported error (0x800CCC0F) : ‘The connection to the server was interrupted. If this problem continues, contact your server administrator or Internet service provider (ISP).
  4. No error but would always get the login screen evertime I tried to authenticate to the server to send mail. 

Those are the errors that I can remember.  But in some aspects none of them were related so I was all over the place troubleshooting this.  I also had an ISA machine at the edge so I’m messing with that as well.  I opened up the relay completely to make sure that I could at least do that. Once I confirmed the relay was OK I tightened security back down and the same errors arose. 


First, there weren’t any message boards that were helpful in my 10+ hour search for a solution.  Most were just saying get rid of exchange or make them use OWA.  I knew it was rights but not sure how.  So with the suggestion of a collegue, I created a new user from scratch.  I copy the template that we had made for past user creations.   What do you know, it worked.   I don’t know what right the other users are missing and not sure if I care right now (brain damage).   Since only a handful  of users are the problem, I have no problem re-creating the users for them.  I will try deleteing the user but not the mailbox and then re-marrying the new user to the mailbox and see how that goes.  I’ll keep you posted.

(2/13/08) Update:  We deleted the user and re-created it.  We then reconnected the new user to the old mailbox via system manager and we were able to use both pop and smtp as well. 

4 thoughts on “Can POP mail on my Exchange 2003 server but can’t send mail VIA SMTP

  1. The only fix is to pay those greedy bastards at Microsoft $49.00 or reformat your hard drive and reload all your programs. Has anyone tried using another E Mail program that is not Microsoft?
    Pissed at Bill
    Mickey Yak

  2. I understand your frustration at MS but in the case above, reformatting will not work because it was a server issue. Well, come to think of it, it might have worked because reformatting the whole domain and starting from scratch would have probably worked but not practical.

  3. We’ve all tried using various programs. Most of us use thunderbird now, but we’re open to change.

    FYI the problem involves “SPA” which is microsoft-specific afaik. I suggest investigating “standards” and “smtp tls auth” respectively, and kicking your current server to the curb.

    Hey, is this “Dinosaur Larry” McDowell in the comments? How ya doin man?!

    – jason

  4. Nope, not the same Larry. Thanks for the suggestion, we’ll look into that. Maybe not the kicking the server part : )

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