postfix has transport maps which would force delivery through another one of your servers so that might be part of your solution. You also might be able to do some manual requeuing and then restart the queues with a different sendmail.cf file to a smart host after direct connection has failed. For example, qtool.pl has been used for years to implement various outgoing delivery queues such as 4, 8, 12, 24 hour for sendmail.
Are you trying to get around short term or transient blocking from some of your webserver's ip space when they get caught up in a large cidr block - then route around that problem vs waiting it out with re-delivery? For on demand web servers, it might be easier to use smart relays in their configurations and get the mail off the web servers first and then apply the intelligence on those outgoing smart mail relays and its queuing...not to mention you should gain additional ability to make fewer connections to other mail servers in some instances and/or the ability to throttle your outgoing traffic.Not to mention, its another place to do more intensive outgoing filtering and additional checking. HTH, Jim On Tue, Apr 7, 2015 at 7:30 AM, chris <[email protected]> wrote: > Hello, > > I have a few linux webservers and which each send out SMTP directly . > Currently, the webservers all relay the message directly to receipient and > if it cant then it sends back a NDR to the sender advising the sender the > message could not be delivered. > > I want to scale this out a bit and add 2 "backup" SMTP server but what I > want to do is have the webservers try to deliver the message and also have > both SMTP A and SMTP B as backup relays and I want it so that if the > webserver cannot deliver the message directly then have it try SMTP A, this > server would keep the connection to webserver open and attempt to relay > right away and if it fails REJECT the message so the webserver will try the > next server SMTP B etc etc. > > I am just wondering if anyone knows how to do this or something like it. > As far as MTA I am familiar with exim,postfix,sendmail and not tied down to > a specific one so whichever gives this functionality is fine. > > Basically the problem I am trying to solve is to have a little bit of SMTP > HA sort of so that if lets say the webserver cant reach the receipients > mail server due to some routing problem or lets say if the receipient mail > server has some kind of firewall that was blocking certain ranges of IP's, > then we just want the message to retry on some other SMTP relays which we > can spread out on different networks as backups so we can hopefully just > get the message delivered an alternate way to buy us time to look into why > it couldnt be delivered the normal way. > > I am not really like looking for a commercial solution but rather to build > the setup out of existing open source software. We are all command line > ninjas so we dont need a point and click gui or any appliances :) > > If anyone has a setup like this I'd be curious to pick your brain and see > what worked and didnt work for you. > > TIA > chris > > _______________________________________________ > mailop mailing list > [email protected] > http://chilli.nosignal.org/mailman/listinfo/mailop > >
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