Email problems

Discussion in 'General' started by teves, Apr 10, 2007.

  1. teves

    teves Member


    I have a small email problem which is a bit difficult to locate, because it appears and disapears again without changing anything on the server.

    I have a Suse 10.2 / Ispconfig 2.28 Server running and I am hosting about 150 domains on it.
    Sometimes (very rarely!) my clients get a message like 'max number of connections exceeded' when trying to send/receive mails with an email client.
    The problem then will persist for about 30 minutes and then vanish without a trace ;-)
    The last time that happened I made a netstat -tap, wich you can view in the following:

    Aktive Internetverbindungen (Server und stehende Verbindungen)
    Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
    tcp        0      0 *:mysql                 *:*                     LISTEN      2091/mysqld
    tcp        0      0 *:sunrpc                *:*                     LISTEN      2396/portmap
    tcp        0      0 *:smtps                 *:*                     LISTEN      24900/master
    tcp        0      0 *:hosts2-ns             *:*                     LISTEN      2913/ispconfig_http
    tcp        0      0 *:ftp                   *:*                     LISTEN      2856/vsftpd
    tcp        0      0 *:smtp                  *:*                     LISTEN      24900/master
    tcp        0      0 localhost:826           *:*                     LISTEN      3194/famd
    tcp        0      0 localhost:48972         localhost:826           TIME_WAIT   -
    tcp        0      0 localhost:36388         localhost:sunrpc        TIME_WAIT   -
    tcp        0      0 *:imaps                 *:*                     LISTEN      2478/couriertcpd
    tcp        0      0 *:pop3s                 *:*                     LISTEN      2558/couriertcpd
    tcp        0      0 *:22                    *:*                     LISTEN      2874/sshd
    tcp        0      0 *:pop3                  *:*                     LISTEN      2550/couriertcpd
    tcp        0      0 *:imap                  *:*                     LISTEN      2479/couriertcpd
    tcp        0      0 *:www-http              *:*                     LISTEN      3130/httpd2-prefork
    tcp        0      0 *:smtps                 *:*                     LISTEN      24900/master
    tcp        0      0 *:smtp                  *:*                     LISTEN      24900/master
    tcp        0      0 *:https                 *:*                     LISTEN      3130/httpd2-prefork
    tcp        0      0 whitespace.scr:www-http pd9eb825b.dip0:veracity TIME_WAIT   -
    tcp        0      0 whitespace.scribbl:imap p5089176e.dip0.t-i:vpad VERBUNDEN   4234/imapd
    [COLOR="SeaGreen"]tcp        0      0 whitespace.scribbl:imap VERBUNDEN   25274/imapd[/COLOR]
    tcp        0      0 whitespace.scribbl:imap p5089176e:simple-push-s VERBUNDEN   22141/imapd
    tcp        0   3076 whitespace.scribbl:22 p57A4BCDF.dip0.t-:62818 VERBUNDEN   24664/sshd: wartung
    [COLOR="SeaGreen"]tcp        0      0 whitespace.scribbl:imap XXX.XXX.189.230%538:57825 VERBUNDEN   21789/imapd
    tcp        0      0 whitespace.scribbl:imap XXX.XXX.189.230%538:57824 VERBUNDEN   21785/imapd
    tcp        0     37 whitespace.scribbl:imap XXX.XXX.189.230%538:58779 FIN_WAIT1   -
    tcp        0      0 whitespace.scribbl:imap XXX.XXX.189.230%538:58767 VERBUNDEN   22246/imapd[/COLOR]
    tcp        0      0 whitespace.scribbl:pop3 p5089ffbf.dip.t-d:64045 TIME_WAIT   -
    tcp        0      0 whitespace.scribbl:pop3 p57bd6320.dip.t-d:49168 TIME_WAIT   -
    tcp        0      0 whitespace.scribbl:pop3 p57bd6320.dip.t-d:49169 TIME_WAIT   -
    The green marked lines are the connections to the client in question.
    There do not seem to be entries in the mail logs concerning the problem.

    Any ideas what's going wrong here?
    Do I have to increase the 'max number of connections' somewhere?

    Thank you,
  2. till

    till Super Moderator Staff Member ISPConfig Developer

    Are you really sure that the problem appears when sending mail? The processes you marked above are from your IMAP daemon and not from postfix, so if these processes cause the error message, the error must occur when the client connects with imap. Maybe you can set the limit of simultanious connections to a higher number in your imap client?
  3. teves

    teves Member


    No, I'm not sure.
    It seems to be rather a problem with opening the imap folders while starting the email client software.
    I've changed the MAXPERIP value from originally 4 to 30 in the /etc/courier/imapd file to resolve the problem.
    This seems to fix the problem as far as I can tell now, but I wonder if this might be a security issue.

    regards, Tom
  4. falko

    falko Super Moderator ISPConfig Developer

    I don't think so.

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