> -----Original Message----- > From: centos-bounces at centos.org > [mailto:centos-bounces at centos.org] On Behalf Of Les Mikesell > Sent: Thursday, December 23, 2010 8:30 > To: centos at centos.org > Subject: Re: [CentOS] sendmail / logwatch relaying issue - > driving me crazy > > On 12/23/10 3:44 AM, Götz Reinicke - IT-Koordinator wrote: > > Hallo, *<:-) > > > > may be I'm to tired to see the solution, maybe someone can > give me a hint? > > > > I do have a couple of servers, sending the daily logwatch > report to a > > central support email account. > > > > Some servers do have DNS A and CNAME records. On my mailserver > > relaying for the servers is allowed. > > > > Only one server drives me crazy, getting user unknown or releaying > > denied messages. > > > > Any idea, how to debug this issue? I'd be glad to fix this as a > > christmas gift. I could provide logmessages of course. > > > > If there is an MX record for the target address, it will go > there instead of to > the A record for that name. The receiving server will > usually try to resolve > the From: host address and reject if it can't, so the sender > must have a valid hostname in your DNS (or turn off that > feature). If the receiving server doesn't accept for the > target domain/host address you'd get the relaying denyed > error. If it does accept for the domain but does not have > the user in the address you'd get the user unknown error. > In your /etc/mail/sendmail.mc: dnl # Uncomment and edit the following line if your outgoing mail needs to dnl # be sent out through an external mail server: dnl # define(`SMART_HOST',`mail.pdinc.us')dnl * the mail.pdinc.us resolves to a different ip inside as compared to the public dns entry Each box in your network should send the mail to a central smtp server which allows relaying from your network. We have 2-5 new virtual machines every day, they usually don’t last more than a few days. If we had to admin that centrally either by dns or mail server config we would go bonkers. This way every new machine is responsible for its self. -Jason -- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- - - - Jason Pyeron PD Inc. http://www.pdinc.us - - Principal Consultant 10 West 24th Street #100 - - +1 (443) 269-1555 x333 Baltimore, Maryland 21218 - - - -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- This message is copyright PD Inc, subject to license 20080407P00.