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How do I set default mime type to multipart/alternative ?

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  • Last reply by jklu

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Since a few weeks my thunderbird mails to gmail recipients arrive in their spamboxes by default. Some research discovered that Google won't classify these mails as spam if they are multipart/alternative (text/plain + text/HTML) Now, in the Thunderbird settings I can select either text/plain or text/html as defaults for gmail.com recipients but not both.

I can set the format to both per individual email, but not automatically.

Is there some deep config item which I can use ?

Since a few weeks my thunderbird mails to gmail recipients arrive in their spamboxes by default. Some research discovered that Google won't classify these mails as spam if they are multipart/alternative (text/plain + text/HTML) Now, in the Thunderbird settings I can select either text/plain or text/html as defaults for gmail.com recipients but not both. I can set the format to both per individual email, but not automatically. Is there some deep config item which I can use ?

Chosen solution

Thanks for the hints.

My ISP does not use SPF records which might be part of the problem.

Anyways, after posting the question here I did some more analysis and it turns out that the only way to get Gmail to accept the mail is to use the always-html extension. https://addons.mozilla.org/nl/thunderbird/addon/always-html/

Somehow this does something different than configuring "send options".

If I switch "always-html" off then mail goes to the gmail spam folder and if I switch it on mail arrives in the gmail inbox folder of my gmail contacts.

Thanks again for your efforts.

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Via the Address Book, you can specify whether they prefer Plain or HTML, but if left 'unknown' and your send options state to send both, then even if you compose in HTML, it will get sent as both.

You can choose to send as both. Thunderbird > Preferences > Composition > General tab click on 'Send Options' button

Text format: select ' Send the message in both plain text and HTML' click on ok.

http://kb.mozillazine.org/Plain_text_e-mail_-_Thunderbird

But if your emails are going to spam folders in recipients gmail accounts, it is more likely you are composing emails that gmail believes contains spamlike signs. Maybe it is the subject or content or maybe your email address or IP address has been flagged as sending spam.

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Chosen Solution

Thanks for the hints.

My ISP does not use SPF records which might be part of the problem.

Anyways, after posting the question here I did some more analysis and it turns out that the only way to get Gmail to accept the mail is to use the always-html extension. https://addons.mozilla.org/nl/thunderbird/addon/always-html/

Somehow this does something different than configuring "send options".

If I switch "always-html" off then mail goes to the gmail spam folder and if I switch it on mail arrives in the gmail inbox folder of my gmail contacts.

Thanks again for your efforts.