"...for someone whose time and attention are in high demand -- the ROI may indeed be worth it..." - Inc Magazine
Reserve a conditional & quick reply to important messages & asks. Many reserve these preferred messages for recruiting, fundraising, and marketing their products.
"...any investor is liable to receive pitches from umpteen million not-very-impressive founders. But a startup creator who is happy to pay a small amount of money -- or even just willing to deal with the friction of typing in his or her payment details -- is far more likely to be a serious business prospect than someone who is spamming every single VC with a public email address."