Whenever I get unsolicited PR emails that just aren’t of interest to me, but which appear to have been written in earnest and have clearly been customized for me (instead of the vast majority, which have appear to have no relevance to me or my work), I turn to my canned responses.
For example, a carefully worded, "Thanks for reaching out, but I’m focusing on X at the moment," email can tactfully let the sender know where I stand without burning any bridges. It also saves time while making me look professional and courteous.
For me, getting the most out of my Gmail account came down to knowing my work habits. And as someone whose workday is constantly shifting, that took a few months to figure out. But given the central role that email plays in my work, it was more than worth the effort.