Author: Exim Mailing List Date: To: exim-users Subject: Re: [exim] Greylistd
On Wed, Nov 29, 2006 at 11:05:11AM -0500, gascione wrote:
> All I can tell you is that over the past week we have not received any
> complaints at all for greylisting. I believe that most MTA's will try
> to resend at least once in 5 minutes, at least that is what we are
> seeing. Since our retry timer is set to 120 seconds the mail seems to
> be flowing fine. All I can tell you is what we see. Just prior to
> implementation we sent a general email to every single user on our
> systems telling them what we were doing and asking them to please tell
> us if there were any issues. Aside from normal email issues we have not
> had any complaints from them that are specific to greylisting.
Keep in mind that there *are* sites out there that:
- Dont ever retry at all
- Retry only once after one hour
- Retry once only every 24 hours
- Treat temporary errors as failures
- etc.
>From my experience, the majority of these misconfigured sites tend to be legitimate businesses, usually small or family owned, who haven't
spent enough money on labor to properly set up their mail servers.
Because of this, you'll probably get a complaint here or there from
the intended recipient, but it can take a couple of weeks before they
really notice the problem.
I also think it is a significant mistake to only retain the
information for 24 hours. If a server is proven to retry, why would
you continue to greylist? At that point, the *only* thing you are
accomplishing is delaying email. It is better to leave the
information in there for 30 to 60 days, in my opinion, if you know the
server will retry properly.
On the positive side, just make a whitelist and feel free to throw IP
addresses into it on a whim when you get a complaint. After all,
whitelisting a server from greylisting does no real harm and just puts
it back on par for normal SMTP processing.
