One thing anyone would surely hate is getting email alerts from certain applications like Tagged or WAYN. While you are not subscribed to them, alerts find their way to you mailbox mainly because your friends have chosen to send them to you or because they have allowed access to their email box to which emails are sent to all the addresses found there.
You can always choose to ignore them or classify them as spam. But they still manage to make their way into your inbox which can become irritating as a whole. Some even go to the extent of not remembering if they signed up with these site, considering the many memberships that some people find themselves in.
So all you can do is really delete it if you know what the email contains. Perhaps if something that could screen such emails or limiting the access of allowing such sites from accessing your email box will certainly be a welcome solution. For one, no one wants to get unsolicited spam that becomes irritating at some point.
With that said, perhaps such access can be discussed with your friends as far as using your email as a potential subscriber is concerned. But considering that some friends may have a lot of emails stored, be open to the fact that it may fall on deaf ears.
It is excruciating. But that is the prices of building and having a lot of friend in real life and on the Internet. You just have to deal with it until some proper screening software or procedure comes out.