/**
 * Writing one draft: header safety, message composition, Drafts discovery.
 *
 * Headers are built, not concatenated
 * ───────────────────────────────────
 * `appendDraft` turns caller-supplied strings into real RFC 5322 header lines.
 * A bare CR or LF anywhere in `to`, `from`, `subject`, `inReplyTo` or
 * `references` would end the header being written and start one the caller
 * chose, `Bcc:` being the one that matters, because a draft the owner later
 * sends would carry it. Every field is REFUSED rather than sanitized: silently
 * stripping the newline would send something the caller did not ask for, and a
 * caller that meant to inject learns nothing from a rejection but an attacker
 * whose payload was quietly trimmed learns which filter to try next.
 *
 * The address and subject checks are the SMTP module's own
 * (`validateSmtpAddress`, `validateSmtpSubject`), reused rather than restated
 * so that both ways of getting a message out of this module agree on what is
 * allowed.
 *
 * Finding the Drafts folder
 * ─────────────────────────
 * `"Drafts"` is a guess that is wrong on the most common mail host there is:
 * Gmail's is `[Gmail]/Drafts`, and appending to a literal `Drafts` there
 * creates a new stray folder instead. `selectDraftsMailbox` reads the LIST
 * reply and prefers the folder the server itself flagged `\Drafts`
 * (RFC 6154), which is the only answer that is right by construction.
 */
import type { ImapAppendDraftInput } from './imap-client.js';
/** The fallback when a server tells us nothing about its folders. */
export declare const DEFAULT_DRAFTS_MAILBOX = "Drafts";
/**
 * Validate a header value that is neither an address nor a subject,
 * `In-Reply-To` and `References`, both of which hold message ids.
 *
 * @throws Error with a plain-language message on invalid input.
 */
export declare function validateDraftHeaderValue(value: string, field: string): void;
/**
 * Refuse a draft whose fields would forge headers, before anything is sent.
 * Called by `appendDraft` ahead of any server conversation, and again by
 * `buildDraftMessage` so the composer is safe on its own.
 */
export declare function validateDraftInput(input: ImapAppendDraftInput): void;
/** `Mon, 27 Jul 2026 14:03:05 +0000`, RFC 5322 §3.3, always in UTC. */
export declare function formatRfc5322Date(date: Date): string;
/**
 * Encode a header value as RFC 2047 encoded-words when it is not plain ASCII.
 *
 * A subject in any language other than English is the ordinary case, not an
 * edge one, and mail clients read `=?UTF-8?B?..?=` everywhere while raw UTF-8
 * in a header is only understood by servers that announce RFC 6532 support.
 * Long values are split on character boundaries and folded, because an
 * encoded-word longer than 75 characters is not one.
 */
export declare function encodeHeaderValue(value: string): string;
/**
 * Compose the RFC 5322 message an APPEND uploads.
 *
 * The body goes out as UTF-8 with `Content-Transfer-Encoding: 8bit` rather
 * than being re-encoded, so what the owner later sees in the draft is exactly
 * the text that was handed in. That is also why the caller must count the
 * literal in bytes: this string is longer in bytes than in characters for any
 * body that is not pure ASCII.
 *
 * No `Message-ID` is written. The message has not been sent, and the id that
 * matters is the one the sending path stamps at send time; a second one
 * invented here would never match it.
 *
 * @throws Error when any field would forge a header.
 */
export declare function buildDraftMessage(input: ImapAppendDraftInput, now: Date): string;
interface MailboxEntry {
    readonly name: string;
    readonly attributes: readonly string[];
    readonly delimiter: string;
}
/** Parse the mailboxes out of a LIST reply. Unreadable lines are skipped. */
export declare function parseMailboxList(lines: readonly string[]): MailboxEntry[];
/**
 * Choose the Drafts mailbox from a LIST reply, in descending order of how much
 * the server actually told us:
 *
 *   1. the folder carrying the `\Drafts` special-use attribute (RFC 6154),
 *      the server's own answer, and the only one that survives a mailbox named
 *      in another language;
 *   2. a folder literally named `drafts`, case-insensitively;
 *   3. a folder whose last path segment is `drafts`, this is what finds
 *      Gmail's `[Gmail]/Drafts`;
 *
 * and null when the reply names none of those, which leaves the caller to fall
 * back to the plain `Drafts` name.
 *
 * `\Noselect` folders are skipped throughout: they are path nodes, and an
 * APPEND to one fails.
 */
export declare function selectDraftsMailbox(lines: readonly string[]): string | null;
/**
 * The UID the server assigned the appended message, when it advertises UIDPLUS
 * (RFC 4315) and says so in its tagged reply.
 *
 * Returns null when it does not. Nothing is guessed: a server that reports no
 * UID leaves the caller with `uid: null`, which is true, rather than with a
 * number that points at a different message.
 */
export declare function parseAppendUid(lines: readonly string[]): number | null;
export {};
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