Feature request: add ability to show note about DKIM being missing, perhaps with some icon added

[ell1e]

I love this extension so far! But i noticed when DKIM is missing rather than invalid, so either no Authentication-Results header or it says dkim=none and either local DKIM check disabled or there's no DKIM signature header, there doesn't seem to be an obvious marker which maybe should be there.

It would help if 1. missing was also always shown (at least as an option), and 2. clear icons would be placed next to the DKIM state, e.g. like this:

(I stole the icons from firefox for the purpose of a quick mockup)

[lieser]

Note that you can already set in the display option to always show the DKIM header (https://github.com/lieser/dkim_verifier/wiki/Display-Options#show-dkim-header), which when result in I think what you are asking for:

Also I would recommended to have a look at the sign rules the add-on provides (https://github.com/lieser/dkim_verifier/wiki/Sign-rules).
This allow to specifying that e-mails from certain domains should always be signed, and if not it would result in an even more visible error.

[ell1e]

My apologies that I missed the option to always show it, that's very useful! But I would still suggest that there should be warning icons, and particularly one for "No signature" as well so it stands out. Is there an option for that as well, or would it be possible to add? Maybe it's just me, but I think showing a warning icon for that case would make sense as a default setting.