fix mailto link with multiple emails

Author: DanielYang59

lib/proto/mailto.js

@@ -6,15 +6,22 @@ module.exports.check = (link, opts, callback) => {
     import('node-email-verifier').then((mod) => {
         const emailValidator = mod.default;
         const address = link
-                            .substr(7)      // strip "mailto:"
-                            .split('?')[0]; // trim ?subject=blah hfields
+            .substr(7)      // strip "mailto:"
+            .split('?')[0]; // trim ?subject=blah hfields
 
         /* per RFC6068, the '?' is a reserved delimiter and email addresses containing '?' must be encoded,
          * so it's safe to split on '?' and pick [0].
          */
 
-        emailValidator(address, { checkMx: true, timeout: opts.timeout || '10s' }).then((emailValid) => {
-            if (!emailValid) {
+        // multiple addresses separated by commas
+        const addresses = address.split(',');
+
+        Promise.all(
+            addresses.map(addr =>
+                emailValidator(addr.trim(), { checkMx: true, timeout: opts.timeout || '10s' })
+            )
+        ).then((results) => {
+            if (results.some(valid => !valid)) {
                 return callback(null, new LinkCheckResult(opts, link, 400, null));
             }
             return callback(null, new LinkCheckResult(opts, link, 200, null));