/**
 * Sets the email address for the current user.
 *
 * @param email - Must pass RFC-5322 email address validation. Accepts an explicit null value to
 *   null out attribute.
 *
 * @returns Resolves to a boolean that indicates whether the update was successfully enqueued. Resolves to undefined
 *   if the SDK is not initialized.
 */
export declare function setUserEmail(email: string | null): Promise<boolean | undefined>;