Mailscanner + postfix: dealing with huge loads on distributed mailserver setup

Alex Neuman alex at
Sun Aug 9 19:38:57 UTC 2015

Or have newsletters come out a sub domain with a different MX instead.
On Aug 9, 2015 3:47 AM, "Martin Hepworth" <maxsec at> wrote:

> Another way is to get the marketing crew to use a no-reply type address
> thatll just bounce (you're check invalid recipients in pf right) and
> something like constant contact to send the campaigns in the first place.
> Theyll them way better metrics about opens etc
> On Sat, 8 Aug 2015 at 22:46, <l at> wrote:
>> Hi All.
>> We've got 2 servers with MailScanner+Mailwatch, using Postfix as MTA.
>> Recently we've experienced huge incoming load from distributed locations
>> (our marketing team fired up large newsletter and our corporate server
>> got about 10K "auto-reply" mails in just 20 minutes), and our 'hold'
>> queue got filled up with mails. It caused big delay in recieving
>> legitimate mails, and MailScanner (15 children max.) was buisy with them
>> for about an hour.
>> Is there any way to prevent Postfix from recieving any new mail if there
>> is a clog in Hold queue? For example, if there are more than 500
>> messages, don't recieve new mail and respond with 421 code so clients
>> would go to another mail server?
>> I haven't found any solid measures against it, and I'm considering to
>> write own policy-server for Postfix. It's complicated task (and I'm lack
>> of coding skills), and I want to be sure that I haven't missed vanilla
>> setting for this.
>> So, basically, there two questions: is there some sort of failswitch  to
>> prevent Postfix to get new connections if there is a clog in queue, and
>> how do you deal with huge mailing loads?
>> Thank you.
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