At the company where I work there is a great collaborative culture, and I love that. As part of this culture, we have large Outlook distribution lists (DLs) with hundreds or even thousands of employees being a member. And some of these memberships are mandatory, such as "Everyone" or "ORG-Unit-X" etc.
Now the perk of this is that if you need help, you can send out an e-mail to let's say "All-PMS-In-The-Universe" with your question, and chances are you'll get an answer. And this is great. And our corporate policy is to put the DL into BCC, so we can avoid spamming the rest of the DL who's not interested. (If the DL goes accidentally into TO or CC people usually have the decency to delete the DL after hitting reply-all)
But, sometimes people forget and you'll end up getting a ton of uninteresting messages. Now every once in a while these messages will start spamming your inbox. People sometimes step in and sacrifice themselves by moving the DL into BCC and sending it out, but again, chances are they're also disinterested, but they're willing to take one for the team. Which is a great thing to do, but completely unnecessary.
In Outlook, when you compose an e-mail you have the option to specify an alternative e-mail address that will receive the reply instead of your. Simply provide there the e-mail address of the original sender, and call it a day. That way you'll stop getting the spam as well.