On Oct 16, 2006, at 2:27 PM, Simon wrote:
I reviewed greylisting as a solution in the past, we couldn't accept it
due to
delay and I also read not all email servers will resend properly. So
there is a
chance few legitimate emails will never get redelivered. When you are
running
a business shop, such delays or exceptions are not permitted.
Fortune 500's are greylisting... so why is it not acceptable? Really,
you should try it for a bit and see if it really works.
sqlgrey keeps a list of sites/addresses that have proven themselves good,
and so over time it delays less legit email. It also has a list of known
sites that are broken to whitelist.
When I implemented greylisting for one site, they called in the next
morning sure that email was broken. But after poring through the logs, we
determined that the real issue was simply that they didn't get any legit
email all night, and all the usual spam had been turned away. Once
business hours opened up, their clients started emailing them, and the
legit messages came right in.
It also reduces the load on the SA servers, which makes the delivery time
quicker. In my experience, greylisting averages out better. :)
David Morton
Maia Mailguard http://www.maiamailguard.com
[EMAIL PROTECTED]
I don't use greylisting on my primary MX because I do not wish to delay
mail, but I do on my secondary (not round robin) - and it is very effective
there.
I have one of those SMTP servers (from a major company) that does not retry.
Because of greylisting, I can no longer safely use it for outbound mail -
and don't.
Granted, these links are specific to Postfix, but offer some insight into
lessening the possibility of loosing legitimate mail to greylisting:
http://lists.ee.ethz.ch/postgrey/msg01214.html
http://www.stahl.bau.tu-bs.de/~hildeb/postfix/postfix_greylisting.shtml
Gary V
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