/**
 * `MAIL FROM:` payload resolution from a `SMTPSenderStrategy` policy.
 *
 * Pure functions — no I/O, no shared state. The randomness comes from
 * `crypto.randomBytes` (same primitive used by the catch-all probe local
 * generator in `smtp-verifier.ts`) so probes can't be fingerprinted by a
 * predictable PRNG.
 */
import type { SMTPSenderStrategy } from './types';
/**
 * Resolve a sender strategy into the literal `MAIL FROM:` payload (including
 * angle brackets). Output is ready to drop into `MAIL FROM:${result}`.
 *
 * Examples (with random=`a3x9b7c2deadbeef`):
 *   `{ kind: 'null-sender' }`                            → `<>`
 *   `{ kind: 'fixed', address: 'verify@x.com' }`         → `<verify@x.com>`
 *   `{ kind: 'fixed', address: '<verify@x.com>' }`       → `<verify@x.com>` (already wrapped)
 *   `{ kind: 'random-at-recipient' }` → recipient `alice@gmail.com`
 *                                                        → `<probe-a3x9b7c2deadbeef@gmail.com>`
 *   `{ kind: 'random-at-domain', domain: 'x.com' }`      → `<probe-a3x9b7c2deadbeef@x.com>`
 *   `{ kind: 'custom', build: r => `<x@${r.domain}>` }` → whatever `build` returns
 */
export declare function resolveSenderAddress(strategy: SMTPSenderStrategy, recipient: {
    local: string;
    domain: string;
}): string;