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Re: If you don't want Email, please just say so!

From: Ken Raeburn
Subject: Re: If you don't want Email, please just say so!
Date: Sat, 4 Mar 2006 06:18:20 -0500

On Mar 1, 2006, at 13:10, Alan Mackenzie wrote:
This particular message I'd already tried to send yesterday, at least
once.  I'm tempted to just discard it.

If it is greylisting, generally it also does matching on the sending IP address, so if you're getting dynamically assigned addresses when dialing up, it's going to hurt you. Though, I think many greylisting sites do use much shorter block times -- I think mine is only 4 or 5 minutes.

I detest this "greylisting" which seems to be proliferating through the
community.  Am I supposed to get down on my knees and lick somebody's
boots, just to be allowed to send him email?

There's a lot of experimentation in spam fighting; it's an evolving process. Greylisting is one of the techniques I like, since it (a) can provide a meaningful message back to the SMTP sender in the rare case of a false positive, and (b) won't generate bogus mail in joe- job cases. For most mail configurations that actually comply with the specs, it's transparent except for a delay in limited cases. (This isn't the place for diving into details, but it sounds like you've run across a description anyways.) In fact, I wish the FSF would provide greylisting on their mail servers, at least as an option; the spam I get through my @gnu.org forwarding address is much more than the directly-delivered spam I get at home. (I think the spam I get through FSF mailing lists may *also* be more than the direct-delivered spam.)

Your kind of setup, which tends to get hurt by greylisting techniques, is, as far as I can tell, very uncommon these days. I'm not on any of the mailing lists where lots of sysadmins hang out, but I think yours may be the first case I've heard of with delivery problems from a site actually compliant with the RFCs (i.e., trying to resend, rather than throwing away any email not immediately deliverable).

I know my mail configuration (using sendmail -q over a modem connection)
is anything but up to date.  I keep meaning to get around to getting a
DSL connection in, which I'll manage some day. I also know how revolting
it is to get deluged by spam (hey, I get it too).  But I have to pay
telephone bills by the minute. Each time somebody bounces my mail with
"try again later, luser!" it costs me cents, which steadily accumulate
into Euros.

Some ISPs will provide outgoing mail relays for you; does yours not do this? If not, perhaps you can find some friendly site which will let you relay outgoing mail through them, with some kind of authentication (certificate-based, maybe) so they don't have to act as open relays to do so. Either with normal SMTP, or RFC 2476-style message submission. (I'd offer, if I were set up for message submission and certificate authentication, and if I had more than one mail system, to provide more reliability.)

Please be reasonable, friends! Surely if you're going to say "try again
in an hour!" (or even 5 minutes), you can configure your systems to
accept it, say, up to two days later.  Please?  That way my costs will
only be doubled.

Yeah, I think that usually can be tuned, too (ooh, and mine was kind of on the short side -- now fixed), but like I said above, it's probably a changing IP address that's going to hurt you. Most ISPs and companies will have a relatively small set of outgoing mail servers, or fixed addresses if internal systems send outgoing mail directly, so it usually doesn't hurt. But then there are a handful like you that don't fit that description...

(Of course, I could be guessing wrong, and you've got a static IP address, and it's just some site with badly tuned greylisting parameters that's causing problems for you. But it still sounds like a friendly outgoing relay would help a lot.)


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