export declare enum PopCapabilityType {
    Implementation = "IMPLEMENTATION",
    LoginDelay = "LOGIN-DELAY",
    RespCodes = "RESP-CODES",
    AuthRespCode = "AUTH-RESP-CODE",
    Pipelining = "PIPELINING",
    Sasl = "SASL",
    User = "USER",
    Top = "TOP",
    Expire = "EXPIRE",
    Uidl = "UIDL",
    Stls = "STLS",
    Utf8 = "UTF8",
    Lang = "LANG"
}
export declare class PopCapability {
    readonly type: PopCapabilityType;
    readonly args: string | string[] | null;
    /**
     * Constructs a new pop capability.
     * @param type the type of cabability.
     * @param args the arguments.
     */
    constructor(type: PopCapabilityType, args?: string | string[] | null);
    /**
     * Encodes the capability.
     * @returns the encoded capability.
     */
    encode(): string;
}