Thank You once again for Your support ! We can close that topic, I got all informations.
I really appreciate that mailing list and people which doing support on it ! :) On Fri, Nov 27, 2015 at 3:48 PM, Wietse Venema <wie...@porcupine.org> wrote: > Zalezny Niezalezny: > > Hi, > > > > thank You for Your feedback. > > > > Does this solution is also described by RFC ? > > Load balancers are not described in the SMTP RFC. Nor does the RFC > say how an MTA must be implemented. The RFC gives requirements for > how different SMTP implementations can communicate with each other. > > What I described are requirements so that an MTA can provide SMTP > service behind a load balancer: > > - The server must know the remote SMTP client address so that it > can maintain an audit trail of service requests. and so that > it can make decisions about what service it will provide. > > - The server must know the external SMTP server IP address, so that > it can correctly implement MX preferences without looping. > > > I reviewed RFC but I see that SMTP loadbalancing should be done > > using DNS with proper setup MX records. > > The RFC does not *require* that SMTP receivers have MX records, but > it requires that SMTP senders do MX lookups before doing A lookups. > You can do SMTP with just A records, for example: > > example.com IN A 192.168.1.1 > example.com IN A 192.168.1.2 > > "should" work as well as: > > example.com IN MX 10 mail.example.com > mail.example.com IN A 192.168.1.1 > mail.example.com IN A 192.168.1.2 > > Wietse > > > With kind regards > > > > Zalezny > > > > > > On Fri, Nov 27, 2015 at 2:10 PM, Wietse Venema <wie...@porcupine.org> > wrote: > > > > > Zalezny Niezalezny: > > > > Hi, > > > > > > > > I have a question regarding Domain MX record and physical SMTP > > > Loadbalancer. > > > > > > > > In my infrastructure we have several Postfix machines with local > > > mailboxes. > > > > Each system sending messages to relay servers using internal relay > > > domains > > > > with MX records. My team colleague told me that we will not use > anymore > > > > local relay domains with MX records but Virtual host (with > preconfigured > > > > relay systems behind) and F5 loadbalancer to transfer message from > > > Postfix > > > > servers to the relay hosts. > > > > > > > > I would like to know Your opinion about it ? I know that MX record > has > > > been > > > > designed to avoid problems like E-mail loop etc.etc. Till now its > working > > > > perfect for me. > > > > > > > > Does loadbalancer will not affect smtp communication ? > > > > > > The load balancer MUST provide Postfix with the remote SMTP client > > > IP address. Postfix has support for doing that with: > > > > > > - HAproxy protocol (uses the Postfix smtpd_upstream_proxy_protocol > > > and smtpd_upstream_proxy_timeout features). > > > > > > - nginx (uses the XCLIENT protocol). > > > > > > If your load balancer does not support one of the above protocols > > > then Postfix will not work properly, because all SMTP connections > > > will have the IP addres of the load balancer instead of the real > > > client. > > > > > > To prevent mailer loops, configure: > > > > > > /etc/postfix/main.cf: > > > proxy_interfaces = the loadbalancer external IP address(es) > > > > > > With these things taken care of, load balancers should work. > > > > > > Wietse > > > >
