[BlueOnyx:23560] Re: Milter Greylist

[Chris Gebhardt - VIRTBIZ Internet]

On 1/7/2020 4:39 AM, Richard Sidlin wrote:
>
> Hi List
>
> I have recently purchased the AV Spam package and installed it on my 
> newly built 5210R. I am having trouble with the Milter Greylist. It is 
> set to defer the emails for 15 minutes and then whitelist for 7 days. 
> Problem is, when the originating email tries to send the email again, 
> it keeps being rejected and emails are being delayed by about 12 hours 
> when it eventually lets them through.
>
> I have flushed the SQL database, I have rebooted the server all to no 
> avail. I submitted a support request from the server yesterday but not 
> sure how long it is before I hear back. Anyone have any suggestions?
>
> Thanks.
>
Hi Richard,

Greylisting is widely misunderstood and misused.  Which is unfortunate 
because it can be a great tool.

Without seeing your logs it's impossible for me to tell you with 
certainty, but I have an idea as to what may be happening.   If the 
email is from one of the big email or freemail providers, the way they 
operate is inconsistent with effective greylisting.   The problem is the 
message may be attempted by a machine with one IP address initially, but 
then when it's deferred it is next tried by a different IP address, 
which needs its own 15 minute window, so it's again deferred.   And so 
on.   At some point the message is re-tried by one of the IPs that has 
already knocked on your door and then it's let through.

What we do with our systems is load in the IP addresses or ranges of 
known providers (such as hotmail/outlook, gmail and others) which you 
can commonly find buried in their pages.

Start with the commonality first.  What address(es) are being trapped in 
greylisting?   Where are they being sent from?  Same provider but 
different IPs?   Just look up the ranges, add them into AV-Spam and see 
if that fixes things up for you.

-- 
Chris Gebhardt
VIRTBIZ Internet Services
Access, Web Hosting, Colocation, Dedicated
www.virtbiz.com | toll-free (866) 4 VIRTBIZ