You know what I want, I want a better option when some site says, "to access this file we need to see and download your entire address book". I want more than "yes" or "no". I want "lie to it." Give it an address book full of noise. Tell Dropbox I only know one person, but he's the Pope."
@mhoye There are tools that do this AFAIU, not sure of deets. I think LineageOS or F-Droid would be good places to look.
I tend to answer registration-email-required forms with ceo+<random-value>@domain.tld, where domain and TLD match the site requesting the information.
sales+<string> would likely be even better.
Choke those channels.
("Plus-notation" email addresses typically get delivered to the addressee before the "+" symbol, the rest is used by the sender but ignored by the receiving system.)