Try/catch input sanitization

Pages/Index.cshtml

@@ -67,7 +67,11 @@
                     <p>Agency: @Model.posting.Agency</p>
                     <p>Union: @Model.posting.BargainingUnit</p>
                     <p>Contact Name: @Model.posting.ContactName</p>
+                    @if (!string.IsNullOrEmpty(Model.posting.BoxNumber)) {
                     <p>Contact Email: <a href="mailto:@Model.posting.ContactEmailAddress?subject=Box @Model.posting.BoxNumber, Vacancy @Model.posting.VacancyID">@Model.posting.ContactEmailAddress</a> </p>
+                    } else {  
+                    <p>Contact Email: <a href="mailto:@Model.posting.ContactEmailAddress?subject=Vacancy @Model.posting.VacancyID">@Model.posting.ContactEmailAddress</a> </p>
+                    }
                 </div>
                 <div class="card-footer text-muted">
                     Posted @Model.posting.DatePosted.ToString("d"), Applications Due @Model.posting.DateDue.ToString("d")

Posting.cs

@@ -99,7 +99,10 @@ public class Posting
         ret = ret.Replace("$name", this.ContactName);
         ret = ret.Replace("$vacancy", this.VacancyID);
         ret = ret.Replace("$title", this.Title);
+        if (!string.IsNullOrEmpty(this.BoxNumber))
+        {
             ret = ret.Replace("$box", this.BoxNumber);
+        }
         if (!string.IsNullOrEmpty(data.email))
         {