-----Original Message----- From: centos-bounces@centos.org [mailto:centos-bounces@centos.org] On Behalf Of Les Mikesell Sent: Thursday, December 23, 2010 8:30 To: centos@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 dont 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
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