[pfx] Re: empty from envelope?

Charles Sprickman via Postfix-users:
> 
> 
> > On Jun 7, 2026, at 10:18?AM, Wietse Venema via Postfix-users <[email protected]> wrote:
> > 
> > Charles Sprickman via Postfix-users:
> >> Jun  6 20:37:19 mbox postfix/postscreen[23313]: warning: psc_dnsbl_request: connect to private/dnsblog service: Connection refused
> >> Jun  6 20:37:19 mbox last message repeated 30 times
> > 
> > The dnsblog service in master.cf requires a 'zero' process count
> > limit, and your master.cf is configured accordingly.
> > 
> > This means that some other resource limit is in effect. Perhaps a case of
> > https://web.archive.org/web/20230309014619/http://dilbert.com/strip/1995-06-24
> 
> Oh no! :)

:-)

> I have many jails running on this thing, but overall, not a very
> demanding load.

Perhaps each jail has reduced resource limits (so that it performs
like Dilbert's under-powered computer).

> So self-imposed resource limits? I can check per-user proc counts,
> memory, sockets, anything specific? Should dnsblog be logging
> anything here or I just have to rely on postscreen telling me it
> can't connect to dnsblog?

<wild-ass speculation> 

When a spammer makes a huge burst of connections to your server,
those connections are handled by a postscreen daemon. The large
number of simultaneous connections exhausts some networking resources.
Then, when postscreen requests a connection to a dnsblog process,
that connection request fails with error code ECONNREFUSED.

</wild-ass speculation>

	Wietse
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