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Finding Out Why Non-subscribers are Receiving Mail

Occasionally, you will receive mail from someone saying 'I keep getting messages from your list. I tried to unsubscribe, but it says I'm not on the list.' There are a number of things that can cause this. Possible solutions are listed in order below, and a discussion of possible causes follows.

Possible Solutions

Try unsubscribing them yourself
They user might not quite understand what they are doing. Before trying the complex answers, try the simple one. Unsubscribe them yourself via the web interface. If it fails, read the response message carefully - things like extra spaces can confuse the list server, but it will tell you the problem.

Check the 'From' address on the message
The next thing to do is check to see if the message came from your list. Get the user to send you the message they received. Check to see who it is from. If it is not your list, then someone is forwarding the message, You can either ask them to stop, or remove them from the list.

Using the Individual Delivery option
Mailing lists normally send an identical message to each subscriber on a list. When you are trying to solve a problem like this, it can be useful to send a different message to each subscriber. If you check the 'Individual Delivery' option (on the Mailing List Administration Page), a seperate message will be sent to each user. Each message will have the user's address appended to the first plain text part of the message. It will also have a header added which will contain the original address. This address is the address that the list originally sent to.

Note that this option works best when you send plain text email. Some email programs send both text & HTML in the same message. If you send a message this way, the recipient's mail program may only display the HTML, so you won't be able to see the added text line. Keep it simple, or the line that gets added to identify the message may get stripped away.

The header added is "X-originally-to"

Checking the Received: headers

Another way to figure this out can be to look at the message headers. It doesn't always work, but it can be very helpful.

To do this, you'll need to get them to forward you ALL of the headers (especially the 'Received:' headers). Unfortunately, each email program uses a different command to display these, and most users don't know what it is. (And the ones who do tend to not have this problem!).

Look through the header, there should be some lines that look like this":

Return-Path: YYYYYYY@sdforum.org
Received: from proxy2.ba.best.com (root@proxy2.ba.best.com [206.184.139.13])
	by shell12.ba.best.com (8.9.2/8.9.2/best.sh) with ESMTP id LAA13861
	for <XXXXXXXX@shell12.ba.best.com>; Mon, 1 Feb 1999 11:56:36 -0800 (PST)
Received: from sharon.sigma.net (root@sharon.sigma.net [206.79.203.20])
	by proxy2.ba.best.com (8.9.2/8.9.2/best.in) with ESMTP id LAA19129
	for <XXXXXX@best.com>; Mon, 1 Feb 1999 11:52:02 -0800 (PST)
Received: from lists.sigma.net (medea.sigma.net [206.79.203.18])
	by sharon.sigma.net (8.8.5/8.8.5) with SMTP id LAA05084;
	Mon, 1 Feb 1999 11:50:50 -0800 (PST)
From: YYYYYYY@sdforum.org
Look at the Received: lines. If they have a 'for' entry, that will tell you the address. It may not be the address on your list, but it's a place to start. Check any addresses to see if they are on your mailing list. If not, you can at least see the names of the hosts that received the message, and can look for addresses on that host, in your subscriber list.

Possible Causes

The user subscribed to the list with a variant of their email address.
Many email systems allow a user to use more than one form of their email address. (e.g. xxx@mail.yahoo,com, instead of xxx@yahoo.com, or john_smith instead of jsmith). Search through the list for any addresses on the same host, and see if you can see an obvious similarity. If you are not sure, send an email to the alternate address first, to confirm you have the right one. Once you are sure, delete the alternate address from the list.

The user forgot which address they subscribed with.
Many people have created free email accounts that forward to another account. They might have set this up years ago, and completely forgotten about it.

There are several options listed below for tracking this down. Always check the 'From: ' header first. You can use the Individual Delivery option on the mailing list, or you can check the 'Received:' headers.

Someone (or some list) is forwarding the message to the user
Sometimes people will take your email, and forward it to co-workers, or friends, or even to another mailing list.

There are two options for tracking this down. You can use the Individual Delivery option on the mailing list, or you can check the 'Received:' headers. Again, the 'Received:' headers can help you track this down.

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