If the mailing list you would like to unsubscribe from is in the list on our mailing lists page, then you don't need to use your mail client to unsubscribe, you can do so on the web, using the form on the page. If you still need to find out what email address you used to subscribe, the instructions on this page can help.
First off, if your email address has changed since you subscribed, don't panic! If you are still able to receive mail at your old email address, you can still unsubscribe without having to wait for someone to do it manually! An explanation of how to unsubscribe an email address other than your current one from the mailing lists is located further below.
To unsubscribe from one of those mailing lists, all you usually need to do is send an email to email@example.com (substituting the name of the list for listname — for example, firstname.lastname@example.org).
If you are subscribed to the digest version of the mailing list, you need to send an email to email@example.com.
You will get an automated response with further instructions on how to unsubscribe from the list. You are not simply unsubscribed immediately so that someone can't unsubscribe other people from the list without their consent.
If you get a reply that says you are not subscribed to the mailing list, but you are receiving mailing list traffic, it may be because your email is now coming from a different address than when you first subscribed. (This is determined using the SMTP "envelope sender", not the 'From:' or any other header in your email. So you may not have changed anything, it may have been a change to your mail server or at your ISP.)
To determine what email address is subscribed to the mailing list that you are receiving the messages from, you'll need to inspect the headers of one of those messages. The email address will be encoded in the 'Return-Path' header with the @-sign replaced with an equals (=) sign. For example, if the subscribed email address is firstname.lastname@example.org, the 'Return-Path' header will look something like:
[ ] enable-full-header-cmdoption. Type 'X' in the box to toggle the option on. Type 'E' to exit 'Config', and 'Y' to save changes. The next time you read a message, type 'H' and the full headers will be displayed at the top of the message. Type 'H' again to hide the headers.
To unsubscribe an address like this that is different from what the mailing list software recognizes as your own address, you need to send mail to email@example.com (or -unsubscribe-digest-, if the address is subscribed to the digest format of the list).
Once you have done that, you will receive a message at that email address with instructions on how to complete your unsubscription request.
If you are receiving mail from one of the mailing lists, there should be absolutely no reason that you would be unable to unsubscribe yourself from the list, except for your ability to follow these directions. However, if you find yourself unable to unsubscribe from the mailing list, send an email to firstname.lastname@example.org. Make sure to include the complete headers from one of the messages you have received from the mailing list. Keep in mind that there's a human being at the other end of that last email address, so you'll have to be patient.