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Hi everyone! I am not a Linux Pro, but I have some basic knowledge to get my way around it. I've spent all day trying to configure my Fedora 3 ...
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    sendmail produces 550 error when sending to Comcast.net


    Hi everyone! I am not a Linux Pro, but I have some basic knowledge to get my way around it. I've spent all day trying to configure my Fedora 3 box to send/receive emails using sendmail. And everything seems to work with an exception when I try to send e-mail to my primary mailbox at comcast.net. I keep constantly getting error message from comcast SMTP:
    550 [PERMFAIL] comcast.net requires valid sender domain

    I also tried to configure KMail and it gave me the following result;

    The original message was received at Wed, 23 Mar 2005 02:00:04 GMT
    from localhost.localdomain [127.0.0.1]

    ----- The following addresses had permanent fatal errors -----
    <myemailaddress@comcast.net>
    (reason: 550 [PERMFAIL] comcast.net requires valid sender domain)

    ----- Transcript of session follows -----
    ... while talking to gateway-r.comcast.net.:
    >>> DATA
    <<< 550 [PERMFAIL] comcast.net requires valid sender domain
    550 5.1.1 <myemailaddress@comcast.net>... User unknown
    <<< 503 need RCPT command [data]

    Apparently the problem is in me trying to send the e-mail from localhost.localdomain wich is not known to comcasst DNS.
    When I try to TELNET smtp.comcast.net on port 25 everything goes well and I am able to send an e-mail, but for some reason sendmail just hangs up doing it. I tried to reconfigure sendmail.mc and rebuild sendmail.cf with multiple other options in order to find out where the missing domain name is comming from, but everything was useless. I even reconfigured my Firewall for ports 20, 21 and 25 and disabled SELinux, but again results were the same. I saw lots of people on the web had the same problem with comcast.net using sendmail, but none of them was successfull in explaining if they could fix the problem and more importantly - how. I googled around for hours trying to find the answer, but again no luck there.

    The problem is that if I send an e-mail using KMail, it doesn't let me specify the reply e-mail, and it defaults to the current user on the machine, such as root@localhost.localdomain. But also when I tried to send a mail using php mail() function, where I can specify a From: header it still gives me the same error() and returns the bad mail to apache@localhost.localdomain
    I can send e-mail to ...@comcast.net using Mozilla mail where I can specify who to send e-mail from and then it sends just fine.
    But how can I perform mail() function in PHP? I tried:

    <?php

    $to = 'myemailaddress@comcast.net';
    $subject = 'the subject';
    $message = 'hello';
    $headers = 'From: webmaster@someknowndomain.com';

    $formsent = mail($to, $subject, $message, $headers);
    ?>

    -That's when I got the bad mail to apache@localhost.localdomain

    Once again. I am able to send e-mails using sendmail, but I can't seem to be able to send em to Comcast.Net due to invalid "FROM:" return address specification. So the question boils down to "How do I specify my return address?" for programs like KMail, or for sending e-mail using Apache?
    If you have any idea of how to change it please type me a reply and I'll appreciate it very much.
    Thank you.
    George.

  2. #2
    Linux Engineer adrenaline's Avatar
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    Try using your comcast as your smtp server in your client. For you to do what you want to do Comcast will have to allow your domain to relay. Comcast is bastards when it comes to you having servers. The problem you are facing is the exact reason why I have DSL. I have a special DSL that is twice as fast as cable but it costs twice as much, but I have total control I can resell my connection plus I have 2 dns servers web and mail.

    I think if you don't use your server to send but use it to recieve you will be fine.


    As far as your last question you need to do that with forward and reverse dns and again you are going to run into comcast issues. It you truly want to accomplish what you are trying to do I suggest finding a MA and PA ISP they are usually all to happy to ablige.

    Mike
    Some people have told me they don't think a fat penguin really embodies the grace of Linux, which just tells me they have never seen a angry penguin charging at them in excess of 100mph. They'd be a lot more careful about what they say if they had.
    -- Linus Torvalds

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    That's weird, cause I have IIS SMTP server running on my Windows box on the same cable with no problems. And like I said, when I TELNET comcast server by hand I don't have any issues sending mail this way - and the only time I get 550 message is when I supply my return address that doesn't belong to public domain - This means I shouldn't have those issues using sendmail. I think that the only problem that prevents me from being able to send e-mail is incorrect return address. That is the return address has to reside on a public domain, like www.yahoo.com or something. How can I configure sendmail to do that? I can send mail using Mozilla mail, where I specify the return address myself. But Kmail doesn't allow me to do that. Nor does apache, I think.

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    Yeah as far as using comcast as my SMTP server is exactly what I am trying to escape and that's why I decided to configure my own SMTP. Comcast SMTP limits me in number of connections per hour, it also limits me in a size of message, and the worst of all, it's not nearly as fast as sendmail.

  6. #5
    Linux Engineer adrenaline's Avatar
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    Quote Originally Posted by etrader_x11
    That's weird, cause I have IIS SMTP server running on my Windows box on the same cable with no problems. And like I said, when I TELNET comcast server by hand I don't have any issues sending mail this way - and the only time I get 550 message is when I supply my return address that doesn't belong to public domain - This means I shouldn't have those issues using sendmail. I think that the only problem that prevents me from being able to send e-mail is incorrect return address. That is the return address has to reside on a public domain, like www.yahoo.com or something. How can I configure sendmail to do that? I can send mail using Mozilla mail, where I specify the return address myself. But Kmail doesn't allow me to do that. Nor does apache, I think.
    Maybe I don't understand you question fully. Just because you can telnet into the comcast server doesn't mean anything because you are a comcast customer. If you are trying to telnet as yourdomain.com I bet you couldn't send anything.
    Some people have told me they don't think a fat penguin really embodies the grace of Linux, which just tells me they have never seen a angry penguin charging at them in excess of 100mph. They'd be a lot more careful about what they say if they had.
    -- Linus Torvalds

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    I tried to telnet comcast as mydomain.com and it works just fine as long I supply MAIL FROM: <user@mydomain.com> from a valid domain "mydomain.com" to the header, otherwise it'l take it first but then I get the 550 error after RCPT TO: <user@comcast.net> I believe that exactly where sendmail fails to specify the return address and that's what causes comcast to refuse the transaction. like I said I have no problem to send it through telnet or through Mozilla mail. And also have no problem sending e-mails from my IIS SMTP server in windows. Because in all those cases those programs supply the return address from the correct domain, where sendmail always supplies some local domain name like localhost.localdomain and of cause comcast doesn't know anything about those domains, so it refuses to send the message and generates the famous 550 message telling me that the senders domain isn't correct. I am 100% sure that's what the problem. I just don't know how to fix it. How do I cause the Sendmail to supply the correct return address? HELP!!!! :O

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    For those who's interested, I was able to track a solution for this problem!

    Go to http://mpickering.homeip.net/phpwiki...age/2004-06-24
    and you'll see how you can fix it. The secret was in adding the confDOMAIN_NAME variable to the mc file and then it worked just fine. I knew it wasn't the comcast!!! Well I feel much better after 2 days worth of research.
    Thanks to everyone!

  9. #8
    Linux Engineer adrenaline's Avatar
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    Sorry for the confusion. Nice link, I am glad you figured it out
    Some people have told me they don't think a fat penguin really embodies the grace of Linux, which just tells me they have never seen a angry penguin charging at them in excess of 100mph. They'd be a lot more careful about what they say if they had.
    -- Linus Torvalds

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