To product designers: In practice, you should really avoid using the "sending a reply email message" part. Especially these days when people have multiple email addresses, it can very quickly break down.
This happens often to me:
* Get email that I'd like to unsubscribe to
* Look for unsub info -- directed to "reply to this email" or, almost as bad, "enter your email address"
* Follow instructions
* Receive notice saying "Sorry, the email you entered [sent from] is not in our database"
Well thanks. We've gotten nowhere.
So the right way to design this should be a simple unsubscribe link w/ a unique token that executes the request upon clicking.
At worst, you can do what Constant Contact does and require the email address to be entered, but still provide a hint (i.e. "a....email@example.com"). This is still somewhat annoying, but I understand why they do it -- it likely reduces net unsubs since there's a second step involved. Pushing it, but thinking as a business owner as well, I get it.
I agree with your point about unsubscribe links, but I don't see how it's not immediately obvious which of your multiple E-Mail addresses you need to unsubscribe with since it's going to be the one the mail was sent to.
For those with vanity URLs and GMail - the trick I use to manage unsubscribes better is to enable 'catch-all address' and registering for new accounts by their URL and TLD, e.g. news_ycombinator_com@URL.com, or kennethcole_com@URL.com, etc.
Two benefits - 1) easier to remember my login per site and 2) if I start getting spammed as a result of my info being shared with third-parties, I can attribute the original offender to the e-mail address.
Also a good way to get vast amounts of dictionary attack spam. One of the mail domains I host was accepting mail to all addresses for some years, and this seems to have attracted even more spam: the volume of junk it gets is disproportionately huge compared to the other similar domains.
My mail server allows -- as an alternative to + so my users can work around braindead address regexes.
You also get few hundred "new viagra price" in your spam folder sent to HjvhBYgVqJ@your.domain. You'll never find firstname.lastname@example.org in that mess. Even worse is that you get bounced spam emails sent to email@example.com with from header sent to HjvhBYgVqJ@your.domain and spam filter doesn't see them as spam.
Gmail accepts multiple forms of email addresses for a single account. firstname.lastname@example.org is identical to email@example.com. I often get subscribed to email lists I don't want using a variant of Gmail address that I never use. Also, plenty of people using forwarding addresses; it may not be clear which address was the target.
Either you or your friend is misspelling their address (more common than you might think, I get opt-in mailing-list mail for firstname.lastname@example.org, intended for email@example.com), or you've encountered a bug.
Google's own firstname.lastname@example.org mailing list has this as the "To:" field:
And at the bottom of the message:
To unsubscribe from this group, send an empty message.
I had to ctrl-u and check the "Delivered-To:" and "X-Forwarded-For:" headers before I could unsubscribe.
(I'd tried to unsubscribe previously but the subscribed email account forwards to my main account so replying with an empty message didn't work. This thread prompted me to dig a little deeper and finally get one less piece of email per day - thanks HN!)