--- a/mail/components/compose/content/MsgComposeCommands.js
+++ b/mail/components/compose/content/MsgComposeCommands.js
@@ -3044,16 +3044,18 @@ function addRecipientsToIgnoreList(aAddr
   if (gSpellChecker.enabled)
   {
     // break the list of potentially many recipients back into individual names
     var hdrParser = Components.classes["@mozilla.org/messenger/headerparser;1"].getService(Components.interfaces.nsIMsgHeaderParser);
     var emailAddresses = {};
     var names = {};
     var fullNames = {};
     var numAddresses = hdrParser.parseHeadersWithArray(aAddressesToAdd, emailAddresses, names, fullNames);
+    if (!names)
+      return;
     var tokenizedNames = new Array();
 
     // each name could consist of multiple word delimited by either commas or spaces. i.e. Green Lantern
     // or Lantern,Green. Tokenize on comma first, then tokenize again on spaces.
     for (name in names.value)
     {
       var splitNames = names.value[name].split(',');
       for (let i = 0; i < splitNames.length; i++)