In 1952 Nancy Mitford asked Evelyn Waugh, “What do you do with all the people who want interviews, with fan letters & with fans in the flesh? Just a barrage of nos?” He responded with his own rules:

(a) Humble expressions of admiration. To these a post-card saying ‘I am delighted to learn that you enjoyed my book. E. W.’
(b) Impudent criticism. No answer.
(c) Bores who wish to tell me about themselves. Post-card saying ‘Thank you for interesting letter. E. W.’
(d) Technical criticism, eg. One has made a character go to Salisbury from Paddington. Post-card: ‘Many thanks for your valuable suggestion. E. W.’
(e) Humble aspirations of would-be writers. If attractive a letter of discouragement. If unattractive a post-card.
(f) Requests from University Clubs for a lecture. Printed refusal.
(g) Requests from Catholic Clubs for lecture. Acceptance.
(h) American students of ‘Creative Writing’ who are writing theses about one & want one, virtually, to write their theses for them. Printed refusal.
(i) Tourists who invite themselves to one’s house. Printed refusal.
(j) Manuscript sent for advice. Return without comment. …
(k) Autograph collectors: no answer.
(l) Indians & Germans asking for free copies of one’s books: no answer.
(m) Very rich Americans: polite letter. They are capable of buying 100 copies for Christmas presents.

“In case of very impudent letters from married women I write to the husband warning him that his wife is attempting to enter into correspondence with strange men. … I think that more or less covers the field.”