Plain Text not showing when sending an email with an attached file in C#

Question

When I send an html email with an attached file, Plain Text on Thunderbird doesn't show anything, especially when an attached file is docx, pdf, or etc. txt file was okay when I tested though.

It works well if I don't attach any files, Thunderbird correctly shows Html Text and Plain Text if I switch its view setting.

using(var mail = new MailMessage()){
    // ...omit
    var alternateView = AlternateView.CreateAlternateViewFromString("<h1>TEST</h1>", Encoding, MediaTypeNames.Text.Html);
    alternateView.TransferEncoding = TransferEncoding.SevenBit;
    mail.AlternateViews.Add(alternateView);

    mail.Attachments.Add(new Attachment("path to a file"));
    // ...omit
}

I tried https://stackoverflow.com/a/2828438/366049 but no luck.

--EDITED--
As Caius Jard suggested, I tried the following and the results are below.

setting it as the main body + the HTML as an alternateview
It works, but this means I have to prepare plain text and html text. If I don't attach any files, Thunderbird shows plain text which is from html text removing tags. I want this behavior all the time since input text is made by our users. Otherwise I need to retrieve plain text from html.
setting both the text and the HTML as alternate views, no main body
Both Plain Text and Html Text settings in Thunderbird show the text alternate view.
setting the text as both the main body and a text alternateview as well as having an HTML alternateview
Thunderbird shows the text alternate view even if I switch its view setting.

According to these experiments, a plain alternate view is superior than an html alternate view and a main body.

I do set MIME type on the alternateView in the code above. – Yoo Matsuo Aug 08 '17 at 06:27 — Yoo Matsuo, Aug 08 '17 at 06:27
How does one CRAFT a MINE type? ;) – Caius Jard Aug 08 '17 at 06:27 — Caius Jard, Aug 08 '17 at 06:27

score 0 · Accepted Answer · answered Aug 08 '17 at 06:26

0

Though your question doesn't seem to contain example code that demonstrates how you set the plaintext, try

setting it as the main body + the HTML as an alternateview
setting both the text and the HTML as alternate views, no main body
setting the text as both the main body and a text alternateview as well as having an HTML alternateview

I'd be interested to know which of these works out for thunderbird..

answered Aug 08 '17 at 06:26

Caius Jard

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this should be a comment, not answer – Jacek Cz Aug 08 '17 at 06:29
This is not a direct answer, but I decided to put a message on a mail body like saying "Please change the view setting to the html view", and it should work for now. – Yoo Matsuo Aug 08 '17 at 07:02

Plain Text not showing when sending an email with an attached file in C#

1 Answers1