I am not at all surprised to see one of the emails you got matches exactly (other than the extension name) one from the linked post. Definitely a lot of this crap is heavily automated.

> I'm a fan of [extension name] and I really like how convenient and useful it is.

> Have you considered offering promotional spots to those interested in promoting their products on your extension? I'm interested in promoting my own extension on [extension name] and would love to discuss this possibility with you.

> Let me know if you're open to this.