Change your default response
It happens every time, doesn't it? You buy something from a different retailer than usual and the store immediately adds your email to every mailing list they have. And then they email you every day, sometimes even more than daily. Isn't that just so aggravating? What a pain in the...
Okay, it's a bit of a pain. But it's also completely predictable and easy to change.
Here's my old response for these situations: "Ugh! I hate when companies I buy something from add me to these mailing lists and then I get bombarded with a million emails. As if I'm going to buy from them again right away! Now I don't ever want to buy anything from them again! Why do companies do that? It's such a stupid practice. I'm sure I'm not the only person who gets annoyed by this! Now I have to unsubscribe!"
Here's my new one: "Oh! Here it is, the first of what will probably be many emails from this company. I'll take a moment to unsubscribe now." The end.
Predict the predictable. Then change your default response.