Added 'secondLevelDomains' to 'mailcheck'.

mailcheck/mailcheck.d.ts

@@ -47,6 +47,7 @@ declare module MailcheckModule {
 
     export interface IOptions {
         domains?: string[];
+        secondLevelDomains?: string[];
         topLevelDomains?: string[];
         distanceFunction?: IDistanceFunction;
         suggested?: ISuggested | IJQuerySuggested;