import type { MailOptions, SendResult, SMTPConfig } from "../core/types.js";
/** A single pooled SMTP connection with a persistent session. */
export interface PooledConnection {
    /** Send one message over this connection. */
    send(options: MailOptions): Promise<SendResult>;
    /** Whether this connection is idle and available for work. */
    readonly idle: boolean;
    /** Number of messages sent on this connection. */
    readonly messageCount: number;
    /** Whether this connection can accept more messages before recycle. */
    readonly usable: boolean;
    /** Close the connection and end the SMTP session. */
    close(): Promise<void>;
}
/** Options for creating a pooled connection. */
export interface PooledConnectionOptions {
    /** SMTP configuration for the pooled session. */
    config: SMTPConfig;
    /** Maximum messages before this connection is recycled. */
    maxMessages: number;
    /** Hostname to connect to (may differ from config.host for direct MX). */
    connectHost: string;
    /** Factory that creates the socket adapter for this connection. */
    createAdapter: () => Promise<import("../core/types.js").SocketAdapter>;
}
/**
 * Create a pooled SMTP connection with an open authenticated session.
 */
export declare function createPooledConnection(options: PooledConnectionOptions): Promise<PooledConnection>;