/**
 * Function to check if an email belongs to a sanctioned domain
 * @param {string} email - The email address to be checked
 * @returns {boolean} - Returns true if the email is allowed, false otherwise
 */
export declare function isSanctionedEmail(email: string): boolean;
/**
 * Returns `true` if the given `source` is an email address, `false` otherwise.
 */
export declare function isValidEmail(source?: string | null): boolean;
