Greylisting Addon

Michael Mansour micoots at
Thu Nov 29 04:32:37 GMT 2007

Hi Paul,

"Paul R. Ganci" <ganci at> wrote: Michael Mansour wrote:
> DCC's greylist work fine for *non-MX* servers, however for inbound MX 
> servers which don't have local recipients (but pass the message onto 
> an internal mail server after releasing the message from the embargo), 
> DCC greylist tries to authenticate the recipients with the MX server 
> itself, which of course fails with a "user unknown" and bounces the 
> message to the sender.
> DCC greylist doesn't bother reading sendmail's mailertable to 
> determine where the destination recipient is or to even consider that 
> it's just an inbound MX server and should just greylist (embargo in 
> DCC terminology) the email and then send it on to the real mail server 
> with the inboxes.
> I explained and reported this problem to Vernon but he didn't accept 
> it as a problem, instead tried to convince me that I didn't need MX 
> servers and I should just run a beefy mail server.
> A few emails bounced between us before I gave up trying to explain to 
> him why his greylist 
I run a small ISPs Email system where we have two inbound servers with 
MX records which just forward to the server with the inboxes. I use DCC 
on both servers with greylisting enabled. I do not have the problem you 
describe ... my inbound servers do not try to authenticate users. Are 
you sure that you don't just have some kind of configuration issue?
Pretty sure yes. I've been using DCC for many years and know it pretty well, and sendmail like the back of my hand, I just couldn't get DCC with greylist working on my setup. Messages were bounced with "user unknown" which indicated local recipient checks on the MX servers.
I watch my logs regularly and have never ever seen DCC cause a "user 
unknown" error with a subsequent bounce to the sender. I have been 
running DCC with greylisting enabled for the last two years now.
Yes, I'm sure it works for people, all I'm saying is it didn't work for me. I spent two weeks trying to make a go of it before giving up with it.

I went to milter-greylist and had something in production the second day. It was straight forward to setup (and so is DCC) but gave me no trouble, it just worked.

> He's a cluely guy and knows his stuff, but I just couldn't get through 
> to him, he simply didn't accept the setup I had as a valid setup. Go 
> figure.
I have had several Email exchanges with him. I agree with your 
assessment but would add that he is just a stubborn guy who believes his 
way is the only way. While I like DCC a lot if you indicate to Vernon 
that you wish to use it in a different way than he envisioned you will 
only get grief.
:) I couldn't have put it better myself.


Paul (ganci at

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