Users receive cdo messages as plain text

Question

I have an ASP.NET application that needs to send emails. At first I used System.Net.Mail and everything was good. My application could send html messages and people received them just fine.

But then we added a new web server and that web server needed SSL to send the email using a different smtp server. So I had to use cdo messages instead of System.Net.Mail. See How can I send emails through SSL SMTP with the .NET Framework?

And now something very strange happens. The original server is sending emails in plain text, while the second server is sending emails in html. Both servers are using the exact same code (at the end of this post). The only difference is that the original server doesn't need username and password while the second one does.

Another difference is the first server is running Windows Server 2008 R2 and the second server is running Windows Server 2012. But I don't think cdo has changed between those two releases, right?

I don't know how to troubleshoot this. The problem is not in the code because the second server works fine, and it is not in the smtp server that the first server is using because it was working fine with System.Net.Mail. Any idea??

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Configuration;
using System.Net.Configuration;
using System.Net.Mail;
using System.Runtime.InteropServices;

namespace Kernel
{
    public class cdoMessage
    {
        public String Host;
        public String Username;
        public String Password;
        public Int32 Port;
        public Boolean EnableSsl;
        public String From;
        public MailAddressCollection To;
        public Boolean IsBodyHtml;
        public String Subject;
        public String Body;
        public MailAddressCollection Bcc;

        public cdoMessage()
        {
            SmtpSection settings = (SmtpSection)ConfigurationManager.GetSection("system.net/mailSettings/smtp");

            Host = settings.Network.Host;

            Username = settings.Network.UserName;

            Password = settings.Network.Password;

            Port = settings.Network.Port;

            EnableSsl = settings.Network.EnableSsl;

            From = settings.From;

            To = new MailAddressCollection();            

            IsBodyHtml = false;

            Bcc = new MailAddressCollection();
        }

        String s(String e)
        {
            return "http://schemas.microsoft.com/cdo/configuration/" + e;
        }

        public void Send()
        {

            CDO.Message message = new CDO.Message();

            try
            {
                message.Configuration.Fields[s("smtpserver")].Value = Host;

                message.Configuration.Fields[s("smtpserverport")].Value = Port;

                message.Configuration.Fields[s("sendusing")].Value = CDO.CdoSendUsing.cdoSendUsingPort;

                if (Username == null && Password == null)
                {
                    message.Configuration.Fields[s("smtpauthenticate")].Value = CDO.CdoProtocolsAuthentication.cdoAnonymous;
                }
                else
                {
                    message.Configuration.Fields[s("smtpauthenticate")].Value = CDO.CdoProtocolsAuthentication.cdoBasic;

                    message.Configuration.Fields[s("sendusername")].Value = Username;

                    message.Configuration.Fields[s("sendpassword")].Value = Password;
                }

                if (EnableSsl)
                {
                    message.Configuration.Fields[s("smtpusessl")].Value = "true";
                }

                message.Configuration.Fields.Update();

                message.From = From;

                // ToString works just fine.
                message.To = To.ToString();

                message.BCC = Bcc.ToString();

                message.Subject = Subject;

                if (IsBodyHtml)
                {
                    message.HTMLBody = Body;
                }
                else
                {
                    message.TextBody = Body;
                }

                message.Send();
            }
            finally
            {
                Marshal.ReleaseComObject(message);
            }
        }
    }
}

I see `IsBodyHtml = false;` so the body gets written to the TextBody unless you explicitly set the `IsBodyHtml` property to true. Can you add the code that uses this class cdoMessage? Is it also the same on both machines? — flup, Dec 06 '13 at 00:20
Thanks for the response! I was giving up on this one. IsBodyHtml is set to true before calling Send, and the code is exactly the same in both machines. One works, the other doesn't. I had this wild idea of replacing the dll in the 2008 server with the one from 2012 and see what happens. I will keep you posted. — BCartolo, Dec 06 '13 at 21:37
Can we blame the new smtp server perhaps? Might it convert your message back to plain text? Have you tried sending a HTML email through the server using a normal client? — flup, Dec 06 '13 at 22:23
In server A, when using System.Net.Mail emails are in HTML, but when using cdo, they are in plain text. — BCartolo, Dec 07 '13 at 18:07
Why not use explicit SSL, on port 587 instead of 465? That's supported by System.Net.SmtpClient and in fact is the only method actually defined in a standard — Panagiotis Kanavos, Dec 12 '13 at 09:24
You could also use an SSL wrapper like [stunnel](https://www.stunnel.org/index.html) to encrypt the entire connection in SSL. `stunnel.conf` includes an example of forwarding a local connection to port 25 to gmail's port 465 — Panagiotis Kanavos, Dec 12 '13 at 09:45
Unfortunately, I don't control the email server. I can't change the SSL type. I will take a look at stunnel, but first I will try the answer below. Thanks — BCartolo, Dec 12 '13 at 14:47

score 1 · Accepted Answer · answered Dec 14 '13 at 00:12

Here is a free library that has SSL\TLS support for POP3, SMTP, IMAP in explicit and implicit modes. Obviously I haven't used it but it appears fairly sophisticated for what it does. It's definately worth a try for the price.

http://visualstudiogallery.msdn.microsoft.com/28b96cd4-b755-48a0-b686-9abb7d5607a8

drankin2112 · Answer 2 · 2013-12-13T00:42:26.380

0

Try setting both .HTMLBody and .TextBody to the values that you want. Ideally different versions for plain text and html. Usually, if one is absent it is the html. The Html is considered the "alternative" display text in most readers, at least it was back in the day. Perhaps the different SMTP server handles missing email fields differently.

If that doesn't fix the problem, send plain text in both fields and see if both servers treat it the same.

If that doesn't work, forward the email from server B through server A and vice verse and see what happens. Even if you just do it manually from your email reader. It may very well be a setting on the second SMTP server that is sending as plain text by default.

Look at the MIME headers in the messages that are received from both servers. Look for differences so that you know what is actually different.

You should eventually be able to nail down what's happening and where.

UPDATE

Put in your credentials and give this a try. It sent mail to my gmail address over SSL. Try sending to your old server.

    public bool SendMail() {
        var client = new SmtpClient("smtp.gmail.com", 587) {
            Credentials = new NetworkCredential("your email", "password"),
            EnableSsl = true
        };

        MailMessage message = new MailMessage(
            new MailAddress("from email address"),
            new MailAddress("to email address")) {
                Body = "This is a test e-mail message sent using SSL ",
                Subject = "Test email with SSL and Credentials"
            };

        try {
            client.Send(message);
        } catch (Exception ex) {
            Console.WriteLine("Exception is:" + ex.ToString());
        }

        return false;
    }

edited Dec 13 '13 at 00:42

answered Dec 10 '13 at 22:27

drankin2112

4,715
1
15
20

Thanks! I will try your suggestions & see. I did look at the headers for both the good and the bad server before posting the question. The bad server is stripping the html tags and sending the message in plain text: Content-Type: text/plain; charset="iso-8859-1" X-MimeOLE: Produced By Microsoft MimeOLE V6.1.7601.17609 Plain text While the good server: Content-Type: multipart/alternative; boundary="----=_NextPart_000_0000_01CEF687.3EEA8DA0" X-MimeOLE: Produced By Microsoft MimeOLE V6.3.9600.16384 Plain text ------=_NextPart_000_0000_01CEF687.3EEA8DA0 Content-Type: text/html Formatted text – BCartolo Dec 12 '13 at 14:57
So I set .TextBody to
A
and then the same to .HTMLBody and I see the html tags in the email as characters, not rendered. Unfortunately, the servers are behind firewalls so I can't cross test – BCartolo Dec 12 '13 at 23:08
does the html version come through in the MIME content? in other words, are both text and html versions coming through and the reader is displaying the wrong one? if so, are you using the same email reader to view the emails from both servers? if this isn't the problem, do you host your own email servers or are they maintained by a vendor? if vendor, contact them and explain the problem, if not you will need help from your system administrator. if the MIME contents are the same, it's your reader. If they are different, it is the mail server. – drankin2112 Dec 12 '13 at 23:39
Thanks. The html part is gone, only the plain text with the tags on it remains. – BCartolo Dec 12 '13 at 23:43
did you try Panagiotis Kanavos's solution? – drankin2112 Dec 12 '13 at 23:50
check out my update and see if it works. I sent you some code that uses SSL with the SmtpClient class. please thumbs up if it works. – drankin2112 Dec 13 '13 at 00:13
Yeah, that is what I originally did. But the problem is that there are two types of SSL connections and only one is supported by System.Net.Mail, my server requires the other one. That's why I had to switch to cdo. – BCartolo Dec 13 '13 at 23:50

score 0 · Answer 3 · answered Dec 12 '13 at 15:16

0

I recall this happening with weird reason:

If lines in the body are too long SMTP service will send the mail as plain text even we're sending it as HTML. Try breaking the mail body down to shorter lines by inserting \n line breaks. Though I can't say how long the lines may be.

answered Dec 12 '13 at 15:16

fan711

716
3
13

Thanks! This might be the problem. I will test and see. – BCartolo Dec 12 '13 at 17:51
This didn't work. I tried an email with
A
but it is still showing up as plain text. – BCartolo Dec 12 '13 at 23:04

Users receive cdo messages as plain text

3 Answers3

A

A