Add HTML support/text styling in k-9 Mail/Thunderbird Android

[nose_gnome]

HTML support needs to be added to composition in K-9 mail/Thunderbird android, to allow text formatting, changing fonts, text colours, strike-through, bold and everything else that would be possible from added html support in the compose window.

Also, allowing HTML in the signature would be useful.

I'm surprised this hasn't already been added

[Jon]

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[bona]

I often want to paste an image in the middle of a sentence,

so this feature is much appreciated!

[47949b26a7c452a]

HTML signatures are one of the main things keeping me from using Thunderbird as my primary mobile email client. I need properly formatted signatures for my work addresses (hyperlinks in particular), and unfortunately that's only possible with HTML/rich text.

[Parm]

Hi, Recently installed Thunderbird in my android, I would like to know where, how of any useful information to start contributing code to the app, I would like to use HTML signature as in my Thunderbird desktop so, I think I can contribute to make this happen in the android version, I'm android developer.

[matj1]

I suggest that Thunderbird on Android would allow using purely structural HTML tags like p, em, h1–h6, ul, pre, code, blockquote rather than visual tags or CSS. My experience is that email clients have various viewports and colorschemes, so specifying explicit colors, sizes and fonts likely messes up someone else's rendering of the email. It is better to give the email some suitable structure, and the email clients would suitably interpret that structure.

[matj1]

I would like to be able to use Markdown for formatting or view and edit the raw HTML of the email in Thunderbird on Android. These allow clean formatting so I would know that there are no unintended consequences of some invisible HTML tags. Most HTML editors for emails don't allow to see the structure, and I consider the structure of a HTML document important.

In desktop Thunderbird, I use an extension to edit the email in HTML. On Android, I use FairEmail to write emails in Markdown, but I would switch to Thunderbird on Android of it has such formatting capabilities.

[BelFox]

Dear Thunderbird Android team,

I urge you to take a bold move and support basic formatting options in the Android version.

No formatting at all is not acceptable in a 2026 email client!

[willowen100]

I too would like to see text formatting with support for HTML and Markdown. Markdown has become increasingly popular in note apps, forum platforms and even WhatsApp!

Additionally, having the ability to insert images and tables etc into the body of the text would a bonus.

I was linked to this forum thread from a GitHub feature request from almost 10 years ago food found here 

My highly recommended note app Notesnook's GUI works really well. Note sure if something like that could be implemented.

[avinashk]

There are multiple GitHub issues related to this. I understand that implementing a rich text editor is a complex and major task. However, a perhaps intermediate/temporary solution might be to implemnent markdown parser in the composer. this would atleast take care of rhe basic functionality we all need. 

Or atleast the ability to paste rich text formatted in some other app.