CouldNotCreateMail with attachment

[cylorijin]

Hi! I have the following code. When i add the attachment the mail can not be created. Windows 10 UWP. With EASendMailRT it works.

        using (SmtpClient client = new SmtpClient("smtp.host.com", 465, true, "my@email.com", "123"))
        {
            var emailMessage = new EmailMessage();

            emailMessage.To.Add(new EmailRecipient("to@email.com"));
            emailMessage.Subject = "A new email has arrived";
            emailMessage.Body = "Export File";

            Windows.Storage.StorageFolder storageFolder = Windows.Storage.ApplicationData.Current.LocalFolder;
            Windows.Storage.StorageFile attachmentFile = await storageFolder.GetFileAsync("export.txt");

            if (attachmentFile != null)
            {

                var stream = RandomAccessStreamReference.CreateFromFile(attachmentFile);

                emailMessage.Attachments.Add(new EmailAttachment(attachmentFile.Name, stream));

                SmtpResult ex = await client.SendMailAsync(emailMessage);

                var messageDialog = new MessageDialog("Email Code: " + ex.ToString());

                await messageDialog.ShowAsync();
            }
        }

[Vangos]

Hello and thank you for creating the ticket. Could you please provide me with the following information:

1. What is the SmtpResult code?
2. What is the size of the attachment?

[cylorijin]

Hi! Thanks four your response. The SmtpResult is "CouldNotCreateMail" and the file size is 16KB.

[jbastidasDNC]

Hi, any updates about this issue?. I am having same problem.

[Vangos]

I have not been able to reproduce. I assume the mail server could block potential attachments.

[jbastidasDNC]

Hi again. In my case I am using 1and1 smtp server (smtp.1and1.es). It was responding 501 syntax error - line too long after I send message section:

SmtpResponse repsonseMessage = await Socket.Send(await BuildSmtpMailInput(message));

I notice it was because fileEncoded was very long to 1and1 smtp restriction. So I modifyed BuildSmtpMailInput method

                string fileEncoded = await _encodeToBase64(attachment.Data);
                List<string> splitData = new List<string>(Regex.Split(fileEncoded, @"(?<=\G.{100})", RegexOptions.Singleline));
                string splitFile = "";
                foreach (var s in splitData)
                {
                    splitFile += s + Environment.NewLine;
                }
                mailInput.Append(Environment.NewLine);
                mailInput.Append(splitFile);
                mailInput.Append(Environment.NewLine);

It worked for me.