Cluster of MailScanners
jrudd at UCSC.EDU
Mon Apr 25 20:58:01 IST 2005
That doesn't help you as much if one goes down, and you're talking
about clients trying to submit messages via SMTP. They'll get errors
when they hit the "send" button if they try the wrong IP address (I
don't know of any email clients that gracefully fail over in that
situation). If they wait a few seconds and try again, they'll get
through ... but, IME, that wont keep you from getting a flood of
complaints when you've got a large user base.
We use a load balancer and an array of identically configured
mailscanner boxes. And instead of limiting submission rates via a
milter, we use the sendmail built-in features for connetion control and
rate control, as well as 2 DNSBLs, and sendmail's Greet Delay.
On Apr 25, 2005, at 10:27, Dhawal Doshy wrote:
> Another way of doing it would be to use the round robin feature of 'A'
> point the 'A' record like this:
> mail IN A IP_ADDRESS_1
> mail IN A IP_ADDRESS_2
> mail IN A IP_ADDRESS_3
> And the 'MX' like this:
> IN MX 10 mail.domain.tld.
> works really well imo. (except dnsstuff complaining about a single mx)
> - dhawal
> Pentland G. wrote:
>> I would agree with Martin except to say that it doesn't guarantee an
>> "even" spread of load.
>> I have 3 MX hosts available to the world and one gets around 50% ->
>> of the load, with the other two each getting just over 20%,
>> my hosts can handle it :-)
>> It all depends how complicated you want to make your life.
>> Martin Hepworth wrote:
>>> normal way of doing this is to have mutliple MX records for the
>>> domain with the same value. That way dns will round robin between the
>>> computers and if one fails others will pick up the work load
>>> John Schmerold wrote:
>>>> Has anyone tried following approach to configuring a cluster of
>>>> MailScanner boxes? 1. Get an account at dyndns.org - They are good
>>>> guys & don't ask for a bunch of money
>>>> 2. Define your mx record to be mx1.dnsalias.net
>>>> 3. Setup as many MailScanner boxes as your daily volume dictates
>>>> (Let's say you're setting up 2 units)
>>>> 4. On the hour, run ddclient on box #1, on the 1/2 hour run ddclient
>>>> on box #2 (see
>>>> http://www.dyndns.org/support/clients/dyndns.html for info regarding
>>>> ddclient) It seems to me that this should help the huge spam attacks
>>>> people are seeing. Will this work, is there a better way?
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