List emails can be a tremendous waste of time if you let them. I'm on a number of different lists, and if I tried to read the emails as they came in every time, I'm not sure I'd be very productive. Rarely, if ever, has anything requiring my personal and immediate action come to me through a lists, and so, I see no reason for them to cloud up my main email inbox.
Instead, I have a folder for each list and use Outlook's rules to send all email from the list to the folder automatically. If there is an issue I'm particularly interested in following, I will modify the rule and add an exception so that the email doesn't go in that box. For example, I have a standing exception for any email where my name is specifically mentioned in the body of the email. This way, those emails show up in my main inbox, and since they're there instead of the usual place, I know there is probably some reason I need to pay more attention to it.
Another exception I have for my list email is if it is an invitation, which I do occasionally get. Those get through to the main inbox.
Once I have them all in their folder, I assign a policy to the entire folder. I have the folder only keep items for 30 days. After that, the emails are automatically deleted. Why? Otherwise, you end up with an unwieldy folder of stale emails. Additionally, if I haven't read the email within 30 days and am that far behind, the amount of unopened email in the folder will become too large for me to even want to try to read it.
This isn't about storage space or anything like that. It's about efficiency. If you have a lot of pointless email in your folders, it can slow down searches and make it harder to sort through search results. Plus, if you have 4000 unread emails, it can act as a mental barrier to not reading email.
I've found that this combination of rules and policies makes it much easier to sort my email in the main inbox and makes getting through to the important stuff easier.