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

[Ken Raeburn <raeburn@gnu.org>]

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.)

Ken