export interface MailgunConfig {
    /**
     * Mailgun API key. Used as the Basic-auth password against the username
     * `api` (or `config.username`).
     */
    apiKey: string;
    /**
     * Sending domain (e.g. `mg.example.com`). Forms the URL path
     * `/v3/<domain>/messages`.
     */
    domain: string;
    /** Default sender address. */
    from: string;
    /** Optional display name; merged as `"<senderName> <from>"`. */
    senderName?: string;
    /**
     * Mailgun region. `'us'` (default) routes to `api.mailgun.net`;
     * `'eu'` routes to `api.eu.mailgun.net`. Ignored when `baseUrl` is set.
     */
    region?: 'us' | 'eu';
    /**
     * Basic-auth username; defaults to `'api'`. Override only for self-hosted
     * deployments that require a different username.
     */
    username?: string;
    /**
     * Escape hatch: explicit endpoint base (e.g. `'https://example.local'`).
     * Takes precedence over `region`. Path `/v3/<domain>/messages` is appended.
     */
    baseUrl?: string;
    /** BYO `fetch` for non-Node runtimes / testing. */
    fetch?: typeof fetch;
}