[lm741]

I hit a similar problems when sending automated internal emails to a Google Groups address at my company. The problem was fixed by adding the following footer: "To unsubscribe, email <my-email-address>."

[danieltillett]

Wow I have to try this trick. I have endless problems with some emails going missing (hotmail and the rest of microsoft’s domains are the worst).

[spinlock]

Uh oh. I created an "unsubscribe" filter a while ago to get rid of spam. It's been great for keeping my inbox clean but I just don't see stuff with an unsubscribe line anymore.

[Lorento]

It's not a good idea to manually create filters that 100% block. You can't think of all the special cases like this.