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Plesk 10.3/Sendmail server, iptables issue on client

Discussion in 'Plesk 10.x for Linux Issues, Fixes, How-To' started by SheldonJ, Oct 25, 2011.

  1. SheldonJ

    SheldonJ Guest

    Hello all.

    I'm currently working with a centos 5.6 based server which is using plesk and qmail smtp server. I dont know if this is a plesk issue or a qmail issue, but since they came together as one in the same I'm guessing this is the place to ask. (I did not do the initial set up so I may be barking up the wrong tree).

    The problem isn't the server itself exactly, rather that on our workstations we are unable to connect send emails with attachments via this smtp service. This appears to be a problem with iptables as after so many packets, iptables views the ACK packets sent from the server after roughly 100kb of data transfer to be unrelated to other packets and begins to drop them.

    The iptables rules are fairly simple, the important ones in use here are as follows:


    If I flush the tables and change the default policy back to accept, all works fine, but this doesn't solve our problem as we need a local firewall on each workstation.

    To be honest I dont think this is solely a iptables issue, rather how it reacts with plesk/qmail since I have tested it with other mail services (all through thunderbird) and this is the only one to fail.

    If anyone can offer any help or advice it would be greatly appreciated.

    Thanks in advance.