When I wrote [about getting a bounce for an address that is not on to the
list because a member must be forwarding it there],
| > Probe messages work only if the refusing site sends you back the text, or
| > sends you back your outgoing subject, or at least returns something that
| > distinguishes one probe message from the others. Prodigy tells you only
| > that such-and-such a user ID is not valid: no text, no Received: headers
| > for the trip from your site to Prodigy, no trace of your Subject:,
| > nothing...
Tom Neff replied,
| Actually there is a way around this problem if you have forwarding/alias
| control at a site, i.e., you can configure your local mail transfer agent
| (MTA) so that many addresses all deliver to you.
Operative word: "if". Write it, as Lulu sang, across the sky with letters
that would sore a thousand feet high. If you don't control the domain's
addressing -- if you are a user on someone else's machine or a customer of
an ISP whose MTA doesn't do VERPs or even suffixing -- then Tom's idea is
something to dream, not to do.
| Instead of (or in addition to) serializing the Subject header in each probe
| message, you also serialize the From: and Errors-To: headers as follows:
|
| From: [EMAIL PROTECTED]
| Errors-To: [EMAIL PROTECTED]
| Subject: List Test #001347
|
| This is a list test message - please ignore it.
Most MTAs ignore Errors-To:, but if you have control over the domain and
can give yourself as many addresses in it as you like, you can use them
as envelope senders; in other words, you're simulating qmail's VERPs, as
I said before and as Dave Sill just mentioned.
| Now even the most uncooperative Prodigy-class mail agent can't help revealing
| which message it's bouncing, because each one will be delivered to a unique
| "userid." Even if they omit a To: header in the bounce, you can examine the
| Received: headers for the delivery address your local MTA saw.
They do omit the To: header, but either their MTA or Smail on WWA was filling
it into Apparently-To: as well as Received: ... for. By using my own logname
and the list's aliases as envelope senders, I eventually tracked down the
culprit. Skip the indented part and go to my next quote from Mr. Neff if
you've read my previous posts of this story:
Based on the timing of the bounces, I knew that the forwarder was a digest-
mode subscriber who was not on the list's sublist. That left 1220 suspects.
With seven envelope sender addresses at my disposal, I divided the 1220
into seven groups of 174 or 175 and sent out seven first-round probes, one
to each group.
About ten minutes later one of them bounced. The addressee of the NDN was
all I had to go by, but it narrowed the field to 175 addresses. Some sub-
scribers replied to probe #1 to assure me they received it, and I answered
thanks, but they didn't have to.
I divided them into seven groups of twenty-five and repeated the process,
assuring recipients in the text that still being there in the second round
didn't mean they were more suspect, just that they were less lucky.
One second-round probe bounced, narrowing it to twenty-five people. I
divided them into seven groups of three or four and sent the third round of
seven probes. One bounced, and there were three people left.
In the fourth round I wrote to them individually with three different
envelope senders, and one bounced. Officer, arrest that woman! I booted
her from the list.
If only the NDNs from Prodigy had included the To: or Subject: or Received:
or even Message-Id: of the undelivered piece (I could have blind carboned
all probes to myself and had a list of which Message-Id: was on whose, or
I could have encoded the addressee into the Message-Id:) it would have been
completely unncessary. OK, so I'd still have had to send 1220 probes, but
not 1220+175+24+3=1422. And I'd have had the answer far sooner and not had
to spend all that extra time on line when I had other things to get done.
| This is particularly easy to do with today's "virtual servers" that forward
| [EMAIL PROTECTED] to the same address.
Not everyone has a personal domain, and I have no intention to shell out the
costs of having one (not only for the registration but also for the MX ser-
vice from an ISP) when I have no need for it except to cope with Prodigy's
poor netizenship.
