microsoft office onSend feature does not allow to send mail if dialog is opened through displayDialogAsync API

问题

I am trying to implement On Send feature in outlook Add-in. All prerequisite are done. It is working fine as normal scenario as mentioned in the documentation.But for my case the requirement is this:

If the Body contains any 'Block Word' I want to show to the user a Dialog box (using displayDialogAsync API) with two options 'Continue' and 'Cancel'. Without dialog box it allows to send Mail but with dialog it is not working.

var mailboxItem;

Office.initialize = function (reason) {
    mailboxItem = Office.context.mailbox.item;
}

function validateBody(event) {
    mailboxItem.body.getAsync("html", { asyncContext: event }, 
   checkBodyOnlyOnSendCallBack);
}

function checkBodyOnlyOnSendCallBack(bodyAsyncResult) {
    var listOfBlockedWords = new Array("blockedword", "blockedword1", "blockedword2");
    var wordExpression = listOfBlockedWords.join('|');

    // \b to perform a "whole words only" search using a regular expression in the form of \bword\b.
    // i to perform case-insensitive search.
    var regexCheck = new RegExp('\\b(' + wordExpression + ')\\b', 'i');
    var checkBody = regexCheck.test(asyncResult.value);

    if (checkBody) {
        mailboxItem.notificationMessages.addAsync('NoSend', { type: 'errorMessage', message: 'Blocked words have been found in the body of this email. Please remove them.' });
        var dialog;
        Office.context.ui.displayDialogAsync(location.origin+'#/urlpath?queryString', {
            height: 40,
            width: 40,
            displayInIframe: true
        }, function(asyncResult) {
            dialog = asyncResult.value;
            //used - Office.context.ui.messageParent() to acces the following block;
            dialog.addEventHandler(Office.EventType.DialogMessageReceived, function(args) {
                 if(args.status){
                   // Allow send.
                   bodyAsyncResult.asyncContext.completed({ allowEvent: true });
                 }else{
                   // Block send.
                   bodyAsyncResult.asyncContext.completed({ allowEvent: false });
                 }
                 dialog.close();
                 event.completed();
            });
        });

    }else{

      // Allow send.
      bodyAsyncResult.asyncContext.completed({ allowEvent: true });
    }

来源：https://stackoverflow.com/questions/50951091/microsoft-office-onsend-feature-does-not-allow-to-send-mail-if-dialog-is-opened