feat: Provide users possible status codes that SendGrid can return

src/SendGrid/Helpers/Errors/ErrorHandler.cs

@@ -87,7 +87,7 @@ public static async Task ThrowException(HttpResponseMessage message)
  /// <returns>Return string with the error Status Code and the Message</returns>
  private static async Task<string> GetErrorMessage(HttpResponseMessage message)
  {
- var errorStatusCode = (int)message.StatusCode;
+ var errorStatusCode = (SendGridStatusCode)message.StatusCode;
  var errorReasonPhrase = message.ReasonPhrase;
 
  string errorValue = null;

src/SendGrid/Helpers/Errors/Model/SendGridErrorResponse.cs

@@ -6,9 +6,10 @@
  public class SendGridErrorResponse
  {
  /// <summary>
- /// Gets or sets the error Status Code
+ /// Gets or sets the error Status Code.<br/>
+ /// Might be any <see cref="System.Net.HttpStatusCode"/>, not just ones in <see cref="SendGridStatusCode"/>.
  /// </summary>
- public int ErrorHttpStatusCode { get; set; }
+ public SendGridStatusCode ErrorHttpStatusCode { get; set; }
 
  /// <summary>
  /// Gets or sets the error Reason Phrase

src/SendGrid/Helpers/Errors/Model/SendGridStatusCode.cs

@@ -0,0 +1,105 @@
+namespace SendGrid.Helpers.Errors.Model
+{
+ /// <summary>
+ /// Each SMTP call you make returns a response.
+ /// 200 responses are usually success responses, and 400 responses are usually deferrals.
+ /// SendGrid continues to retry resending 400 messages for up to 72 hours.
+ /// 500 responses are hard failures that are not retried by our servers.
+ /// </summary>
+ /// <remarks>
+ /// <see href="https://docs.sendgrid.com/for-developers/sending-email/smtp-errors-and-troubleshooting"/>.
+ /// </remarks>
+ public enum SendGridStatusCode
+ {
+ /// <summary>
+ /// Your mail has been successfully queued!
+ /// This response indicates that the recipient server has accepted the message.
+ /// </summary>
+ QueuedForDelivery = 250,
+
+ /// <summary>
+ /// This means the "from" address does not match a verified Sender Identity.
+ /// Mail cannot be sent until this error is resolved.
+ /// </summary>
+ /// <remarks>
+ /// To learn how to resolve this error, see our <see href="https://docs.sendgrid.com/for-developers/sending-email/sender-identity">Sender Identity requirements</see>.
+ /// </remarks>
+ InvalidFromAddress = 403,
+
+ /// <summary>
+ /// Messages are temporarily deferred because of recipient server policy - often it's because of too many messages or connections in too short of a timeframe.
+ /// </summary>
+ /// <remarks>
+ /// We continue to retry deferred messages for up to 72 hours.
+ /// Consider temporarily sending less messages to a domain that is returning this code because this could further delay your messages currently being tried.
+ /// </remarks>
+ MessagesDeferred = 421,
+
+ /// <summary>
+ /// The message failed because the recipient's mailbox was unavailable, perhaps because it was locked or was not routable at the time.
+ /// </summary>
+ /// <remarks>
+ /// We continue to retry messages for up to 72 hours.
+ /// Consider temporarily sending less messages to a domain that is returning this code because this could further delay your messages currently being tried.
+ /// </remarks>
+ MailboxUnavailable = 450,
+
+ /// <summary>
+ /// There is a credit limit of emails per day enforced in error.
+ /// </summary>
+ /// <remarks>
+ /// <see href="https://support.sendgrid.com/hc">Contact support</see> to remove that limit.
+ /// </remarks>
+ MaximumCreditsExceeded = 451,
+
+ /// <summary>
+ /// The message has been deferred due to insufficient system storage.
+ /// </summary>
+ /// <remarks>
+ /// We continue to retry messages for up to 72 hours.
+ /// </remarks>
+ TooManyRecipientsThisHour = 452,
+
+ /// <summary>
+ /// The user’s mailbox was unavailable.
+ /// Usually because it could not be found, or because of incoming policy reasons.
+ /// </summary>
+ /// <remarks>
+ /// Remove these address from your list - it is likely a fake, or it was mistyped.
+ /// </remarks>
+ InvalidMailbox = 550,
+
+ /// <summary>
+ /// The intended mailbox does not exist on this recipient server.
+ /// </summary>
+ /// <remarks>
+ /// Remove these addresses from your list.
+ /// </remarks>
+ UserDoesNotExist = 551,
+
+ /// <summary>
+ /// The recipients mailbox has exceeded its storage limits.
+ /// </summary>
+ /// <remarks>
+ /// We don't resend messages with this error code because this is usually a sign this is an abandoned email.
+ /// </remarks>
+ MailboxIsFull = 552,
+
+ /// <summary>
+ /// The message was refused because the mailbox name is either malformed or does not exist.
+ /// </summary>
+ /// <remarks>
+ /// Remove these addresses from your list.
+ /// </remarks>
+ InvalidUser = 553,
+
+ /// <summary>
+ /// This is a default response that can be caused by a lot of issues.
+ /// </summary>
+ /// <remarks>
+ /// There is often a human readable portion of this error that gives more detailed information, but if not,
+ /// remove these addresses from your list.
+ /// </remarks>
+ MailRefused = 554,
+ }
+}

tests/SendGrid.Tests/Integration.cs

@@ -6059,7 +6059,7 @@ public async void TestHttpErrorAsException()
 
  var errorResponseExpected = new SendGridErrorResponse
  {
- ErrorHttpStatusCode = 503,
+ ErrorHttpStatusCode = (SendGridStatusCode)503,
  ErrorReasonPhrase = "Service Unavailable",
  SendGridErrorMessage = "error message",
  FieldWithError = "field value",