diff --git a/types/mailgun-js/index.d.ts b/types/mailgun-js/index.d.ts
index eaa210e6e1..0c6ef0eef3 100644
--- a/types/mailgun-js/index.d.ts
+++ b/types/mailgun-js/index.d.ts
@@ -128,6 +128,15 @@ declare namespace Mailgun {
 
         type ValidationCallback = (error: Error, body: ValidateResponse) => void;
 
+        interface ValidationOptionsPublic {
+            api_key?: string;
+            mailbox_verification?: boolean | "true" | "false";
+        }
+
+        interface ValidationOptionsPrivate {
+            mailbox_verification?: boolean | "true" | "false";
+        }
+
         interface ValidateResponse {
             address: string;
             did_you_mean: string | null;
@@ -156,13 +165,15 @@ declare namespace Mailgun {
         parse(addressList: string[], callback?: validation.ValidationCallback): Promise<validation.ParseResponse>;
 
         validate(address: string, callback: validation.ValidationCallback): void;
-        validate(address: string, opts: { [key: string]: any }, callback: validation.ValidationCallback): void;
+        validate(address: string, opts: validation.ValidationOptionsPublic, callback: validation.ValidationCallback): void;
         // tslint:disable-next-line unified-signatures
         validate(address: string, isPrivate: boolean, callback: validation.ValidationCallback): void;
-        validate(address: string, isPrivate: boolean, opts: { [key: string]: any }, callback: validation.ValidationCallback): void;
+        validate(address: string, isPrivate: false, opts: validation.ValidationOptionsPublic, callback: validation.ValidationCallback): void;
+        validate(address: string, isPrivate: true, opts: validation.ValidationOptionsPrivate, callback: validation.ValidationCallback): void;
 
-        validate(address: string, isPrivate?: boolean, opts?: { [key: string]: any }): Promise<validation.ValidateResponse>;
-        validate(address: string, opts: { [key: string]: any }): Promise<validation.ValidateResponse>;
+        validate(address: string, opts?: validation.ValidationOptionsPublic): Promise<validation.ValidateResponse>;
+        validate(address: string, isPrivate: false, opts?: validation.ValidationOptionsPublic): Promise<validation.ValidateResponse>;
+        validate(address: string, isPrivate: true, opts?: validation.ValidationOptionsPrivate): Promise<validation.ValidateResponse>;
     }
 
     interface Lists {
diff --git a/types/mailgun-js/mailgun-js-tests.ts b/types/mailgun-js/mailgun-js-tests.ts
index 12bf18e437..e06e683248 100644
--- a/types/mailgun-js/mailgun-js-tests.ts
+++ b/types/mailgun-js/mailgun-js-tests.ts
@@ -33,12 +33,12 @@ mailgun.messages().send(exampleSendData, (err, body) => {});
 let validationResultPromise: Promise<mailgunFactory.validation.ValidateResponse>;
 validationResultPromise = mailgun.validate("foo@mailgun.net");
 validationResultPromise = mailgun.validate("foo@mailgun.net", true);
-validationResultPromise = mailgun.validate("foo@mailgun.net", true, { option: "option" });
-validationResultPromise = mailgun.validate("foo@mailgun.net", { option: "option" });
+validationResultPromise = mailgun.validate("foo@mailgun.net", true, { mailbox_verification: true });
+validationResultPromise = mailgun.validate("foo@mailgun.net", { mailbox_verification: false, api_key: "..." });
 mailgun.validate("foo@mailgun.net", (error, body) => {});
 mailgun.validate("foo@mailgun.net", true, (error, body) => {});
-mailgun.validate("foo@mailgun.net", true, { option: "option" }, (error, body) => {});
-mailgun.validate("foo@mailgun.net", { option: "option" }, (error, body) => {});
+mailgun.validate("foo@mailgun.net", true, { mailbox_verification: true }, (error, body) => {});
+mailgun.validate("foo@mailgun.net", { mailbox_verification: false, api_key: "..." }, (error, body) => {});
 
 const validationResult6: mailgunFactory.validation.ValidateResponse = {
     address: "foo@mailgun.net",