So both GMail and Hotmail have, for some time now -- few years maybe -- been overly aggressive with their spam filtering. As a result, many false positives land in the spam or junk folder.
What is a false positive? It is when an email is incorrectly ("falsely") classified as a spam message. It happens just about every day now. In fact, on Hotmail it has been several weeks since there was a real spam message in the junk folder. Most messages in there are actual legitimate emails.
For an egregious example, recently my stipend payment confirmation was found in the spam folder.
As a result, I have been treating the spam/junk folder as another inbox. (Unified junk box? Anyone? Hello?)
Furthermore, Hotmail deletes messages in the junk folder after 10 days. No way to change this.
As a result, I now check the junk folder more carefully than my inbox. Hm. That is, the junk-mail candidates receive more attention than my classified-as-legitimate emails. Did I loose? Did the attention-economy win?
Let's have a look at those spam messages. On GMail it is not actually that bad (except for that stipend payment). Most spam-classified emails are indeed spam. On Hotmail, I rarely get any spam, and most spam-classified email is actually recurring emails from groups I subscribe to (e.g., equalcitizens.us) and receipts and advertizements from legitimate businesses.
That latter category would actually be easy to fix: In the US there is a law that requires businesses to provide a link allowing you to unsubscribe. You can usually find this near the end of every email they send. I have made use of this in the past, and attribute this as one of the reasons I don't get much spam in the Hotmail account.
So the solution for these should be straightforward: make that link auto-discoverable. Then, the email client can find it, and post a prominent single-click button that lets me unsubscribe if that is what I want.
Obviously, that only works for legitimate businesses, but it would be a huge step forward. Other solutions require having everyone you know or possibly will want to know even if you don't know them yet in your address book. That solution is clearly suboptimal, especially when these are contacts you email with only rarely. Then, they easily slip through the cracks (do I even know everyone's email?), which brings me back to checking that spam folder every day.
Of course, more obvious is to get rid of the spam folder entirely. Also a surprisingly effective option. However, Hotmail does not let you do that (gotta use your email client), and GMail makes it hard. Oh well, let's give those spam messages my full attention. Disunified inbox.