The attempt to fight spam with static filters is futile. The built-in junk mail controls are your best bet. https://support.mozilla.org/kb/thunderbird-and-junk-spam-messages

Christ - Thanks. I want to filter by formatting....not convert to the spam filter systems. I've used them before. My own filters have worked better and generally I get little spam (that isn't filtered.) Only problem are these new ones from the same source that use italics, a particular font, & bold.

A lot are repetitive so I can do it by wording, but formatting would work beautifully.

Anyone have an idea of how I can add that option? There's a customized filter factor option?

It's amazing how obvious this spammer makes their spam with these format styles!

What you are being told is there is basically no support for filtering on what you consider spam identifiers. The Bayesian spam filter does a remarkable job for most people and as it learns it get better. But if you simply don't use it, you will never know if it will do the job for you or not.

You have decided you ignore the automated learning response and are now looking for manual tools. Tools that simply do not exist because the emphasis of filtering is on managing mail, not managing spam. There is another tool for that, in the Bayesian spam filter. If there are any resources available for enhanced spam filtering, it is in the algorithms used by the spam filter that they will be deployed. Not in filtering on font name or style name.

So no you can not filter on body formatting. Nor any of the underlying HTML in the message body. You can only filter on the content as displayed.

Yes there is a customize filter option. It allows you to add additional message headers to be filtered on. For example I have filters that use the yahoo junk header X-YahooFilteredBulk among other manual additions and a few from the filtaquilla addon. https://addons.thunderbird.net/en-US/thunderbird/addon/filtaquilla/

See below for my extended list of filter actions.

None of that makes the message body source available as it is simply not in the data available to filters to act on. Filters get access to the data stored in the MSF database files which load the user interface information, not the message source.