Postfix/Cyrus/MySQL: Can't smtp outside network

Discussion in 'HOWTO-Related Questions' started by TWadmin, Dec 28, 2006.

  1. TWadmin

    TWadmin New Member

    It continues!

    As mentioned previously, I've followed the "Virtual Users And Domains With Postfix, Courier And MySQL (Fedora Core 5)" tutorial.

    Authentication, both plain and SSL, work fine for pop and smtp connections from within my 3 IP address block. Outside of my block, I can still receive mail with pop, but smtp hangs and doesn't send.

    There is no trace of an SMTP connection in /var/log/maillog in these cases. As long as I send from a system within my address block, it shows up as expected.

    This would suggest a firewall issue, but:
    [[email protected] ~]# iptables -L
    Chain INPUT (policy ACCEPT)
    target     prot opt source               destination
    Chain FORWARD (policy ACCEPT)
    target     prot opt source               destination
    Chain OUTPUT (policy ACCEPT)
    target     prot opt source               destination
    The only hardware between the mail server and the world is a switch and a dsl modem.

    I doubt the error from OE would help, but here it is:
    Your server has unexpectedly terminated the connection. Possible
    causes for this include server problems, network problems, or a long period of
    inactivity. Account: 'mail.mydom.ain', Server: 'mail.mydom.ain', Protocol:
    SMTP, Port: 25, Secure(SSL): No, Socket Error: 10053, Error Number:

    I should probably also include this:
    [[email protected] ~]# telnet mail.mydom.ain smtp
    Connected to mydom.ain (
    Escape character is '^]'.
    220 mydom.ain ESMTP Postfix
    ehlo localhost
    250-SIZE 10240000
    250 8BITMIME
    AUTH PLAIN myEncryptedInformationHere
    535 Error: authentication failed
    221 Bye
    Connection closed by foreign host.
    An update to this: the telnet above was from localhost. When trying to telnet from outside to the SMTP port, the session resolves the IP address correctly and attempts to connect, but hangs for a couple of minutes and returns a connection timed out error.

    Any ideas what's up with this?
    Last edited: Dec 28, 2006
  2. falko

    falko Super Moderator ISPConfig Developer

    Is your mail server behind a router? If so, did you forward port 25 from your router to your mail server?
  3. TWadmin

    TWadmin New Member


    Thanks for the reply. I've just figured out the cause.

    In the spirit of continuing to embarrass myself, the problem turned out to be with the laptop I'm using to test the setup. It has Norton AV installed which was set to scan outbound messages. For some reason, it was completely blocking my test messages.

    I hadn't noticed this problem before as this is the first email client I've set up on this machine. No doubt it would have broken if used with any other account as well.

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