/**
 * Options for sending a single email or one item in a batch.
 */
interface MailOptions {
    /**
     * Sender address.
     * - Custom domains (e.g. `hi@aastar.io`) must be verified in the Resend dashboard
     *   (SPF/DKIM/DMARC DNS records) before use.
     * - Without domain verification, use `onboarding@resend.dev` (test only).
     */
    from: string;
    to: string | string[];
    subject: string;
    html?: string;
    text?: string;
    cc?: string | string[];
    bcc?: string | string[];
    replyTo?: string;
    attachments?: Array<{
        filename: string;
        content: Buffer | string;
    }>;
    headers?: Record<string, string>;
    tags?: Array<{
        name: string;
        value: string;
    }>;
    /**
     * ISO 8601 datetime with timezone offset for scheduled delivery.
     * Example: `"2026-06-01T09:00:00+07:00"` or `"2026-06-01T02:00:00Z"`.
     * Must be a future timestamp; Resend rejects past or timezone-ambiguous values.
     */
    scheduledAt?: string;
    /**
     * Idempotency key for agent retry scenarios.
     * Duplicate calls with the same key will not send the email again.
     * Only supported by `send()` — ignored by `sendBatch()`.
     */
    idempotencyKey?: string;
}
/** Result of a successful single send or one item in a batch result. */
interface SendResult {
    id: string;
}
/** Per-item result for sendBatch — includes index for error attribution. */
interface BatchSendResult {
    index: number;
    id: string;
}
/** Error thrown when one or more batch items fail. */
declare class BatchSendError extends Error {
    readonly failures: Array<{
        index: number;
        reason: string;
    }>;
    constructor(message: string, failures: Array<{
        index: number;
        reason: string;
    }>);
}
/**
 * ResendMailer — server-side email utility built on the Resend API.
 *
 * Install: `pnpm add @aastar/email`
 *
 * @example
 * ```ts
 * import { ResendMailer } from '@aastar/email';
 *
 * const mailer = ResendMailer.fromEnv(); // reads RESEND_API_KEY
 * await mailer.send({
 *   from: 'hi@aastar.io',
 *   to: 'user@example.com',
 *   subject: 'Welcome',
 *   html: '<h1>Hello!</h1>',
 * });
 * ```
 *
 * @example Agent tool with idempotency
 * ```ts
 * await mailer.send({
 *   from: 'hi@aastar.io',
 *   to: 'user@example.com',
 *   subject: 'Your receipt',
 *   html: '...',
 *   idempotencyKey: `receipt-${txHash}`,
 * });
 * ```
 */
declare class ResendMailer {
    private client;
    /** @param apiKey - Resend API key from https://resend.com/api-keys */
    constructor(apiKey: string);
    /**
     * Send a single email.
     * @returns `{ id }` — Resend email ID for delivery status queries
     */
    send(options: MailOptions): Promise<SendResult>;
    /**
     * Send a batch of emails (max 100 per request).
     * `idempotencyKey` is stripped per item — not supported by the batch endpoint.
     *
     * @throws {BatchSendError} if any item is missing an ID in the response
     * @returns Results in the same order as the input
     */
    sendBatch(emails: MailOptions[]): Promise<BatchSendResult[]>;
    /**
     * Create a ResendMailer from the `RESEND_API_KEY` environment variable.
     * Recommended for server-side and CI usage.
     * @throws if the environment variable is not set
     */
    static fromEnv(): ResendMailer;
}

export { BatchSendError, type BatchSendResult, type MailOptions, ResendMailer, type SendResult };