Automatically remove duplicate recipients.

Resolves #229

Source/StrongGrid.IntegrationTests/Program.cs

@@ -176,7 +176,9 @@ private static async Task Mail(IClient client, TextWriter log, CancellationToken
  {
  new MailPersonalization
  {
- To = new[] { to1 },
+ To = new[] { to1, to1 },
+ Cc = new[] { to1 },
+ Bcc = new[] { to1 },
  Substitutions = new KeyValuePair<string, string>[]
  {
  new KeyValuePair<string, string>("{{customer_type}}", "friend"),
@@ -190,6 +192,8 @@ private static async Task Mail(IClient client, TextWriter log, CancellationToken
  new MailPersonalization
  {
  To = new[] { to2 },
+ Cc = new[] { to2, to2 },
+ Bcc = new[] { to2 },
  Substitutions = new KeyValuePair<string, string>[]
  {
  new KeyValuePair<string, string>("{{customer_type}}", "customer"),

Source/StrongGrid/Resources/Mail.cs

@@ -229,6 +229,12 @@ public async Task<string> SendAsync(
  numberOfRecipients += personalizations.Sum(p => p?.Bcc?.Count(r => r != null) ?? 0);
  if (numberOfRecipients >= 1000) throw new ArgumentOutOfRangeException("The total number of recipients must be less than 1000");
 
+ // SendGrid throws an unhelpful error when the Bcc email address is an empty string
+ if (string.IsNullOrWhiteSpace(mailSettings.Bcc.EmailAddress))
+ {
+ mailSettings.Bcc.EmailAddress = null;
+ }
+
  var data = new JObject();
  data.AddPropertyIfValue("from", from);
  data.AddPropertyIfValue("reply_to", replyTo);
@@ -244,10 +250,35 @@ public async Task<string> SendAsync(
  data.AddPropertyIfValue("mail_settings", mailSettings);
  data.AddPropertyIfValue("tracking_settings", trackingSettings);
 
+ // This comparer is used to perform case-insensitive comparisons of email addresses
+ var emailAddressComparer = new LambdaComparer<MailAddress>((address1, address2) => address1.Email.Equals(address2.Email, StringComparison.OrdinalIgnoreCase));
+
  // It's important to make a copy of the personalizations to ensure we don't modify the original array
  var personalizationsCopy = personalizations.ToArray();
  foreach (var personalization in personalizationsCopy)
  {
+ // Avoid duplicate addresses. This is important because SendGrid does not throw any
+ // exception when a recipient is duplicated (which gives you the impression the email
+ // was sent) but it does not actually send the email
+ personalization.To = personalization.To?
+ .Distinct(emailAddressComparer)
+ .ToArray();
+ personalization.Cc = personalization.Cc?
+ .Distinct(emailAddressComparer)
+ .Except(personalization.To, emailAddressComparer)
+ .ToArray();
+ personalization.Bcc = personalization.Bcc?
+ .Distinct(emailAddressComparer)
+ .Except(personalization.To, emailAddressComparer)
+ .Except(personalization.Cc, emailAddressComparer)
+ .ToArray();
+
+ // SendGrid doesn't like empty arrays
+ if (!(personalization.To?.Any() ?? true)) personalization.To = null;
+ if (!(personalization.Cc?.Any() ?? true)) personalization.Cc = null;
+ if (!(personalization.Bcc?.Any() ?? true)) personalization.Bcc = null;
+
+ // Surround recipient names with double-quotes if necessary
  personalization.To = EnsureRecipientsNamesAreQuoted(personalization.To);
  personalization.Cc = EnsureRecipientsNamesAreQuoted(personalization.Cc);
  personalization.Bcc = EnsureRecipientsNamesAreQuoted(personalization.Bcc);

Source/StrongGrid/Utilities/LambdaComparer.cs

@@ -0,0 +1,42 @@
+using System;
+using System.Collections.Generic;
+
+namespace StrongGrid.Utilities
+{
+ /// <summary>
+ /// LambdaComparer - avoids the need for writing custom IEqualityComparers
+ /// Usage:
+ /// List&lt;MyObject&gt; x = myCollection.Except(otherCollection, new LambdaComparer&lt;MyObject&gt;((x, y) => x.Id == y.Id)).ToList();
+ /// or
+ /// IEqualityComparer comparer = new LambdaComparer&lt;MyObject&gt;((x, y) => x.Id == y.Id);
+ /// List&lt;MyObject&gt; x = myCollection.Except(otherCollection, comparer).ToList();
+ /// </summary>
+ /// <typeparam name="T">The type to compare</typeparam>
+ /// <remarks>From: http://toreaurstad.blogspot.ca/2014/06/a-generic-iequalitycomparer-of-t.html</remarks>
+ internal class LambdaComparer<T> : IEqualityComparer<T>
+ {
+ private readonly Func<T, T, bool> _lambdaComparer;
+ private readonly Func<T, int> _lambdaHash;
+
+ public LambdaComparer(Func<T, T, bool> lambdaComparer)
+ : this(lambdaComparer, o => 0)
+ {
+ }
+
+ public LambdaComparer(Func<T, T, bool> lambdaComparer, Func<T, int> lambdaHash)
+ {
+ _lambdaComparer = lambdaComparer ?? throw new ArgumentNullException(nameof(lambdaComparer));
+ _lambdaHash = lambdaHash ?? throw new ArgumentNullException(nameof(lambdaHash));
+ }
+
+ public bool Equals(T x, T y)
+ {
+ return _lambdaComparer(x, y);
+ }
+
+ public int GetHashCode(T obj)
+ {
+ return _lambdaHash(obj);
+ }
+ }
+}