Hi,
Thank you for the package! This has a promise of making scientific emailing easy and enjoyable!
I am trying to incorporate math formulas into my emails and I understand that it is turned off (mathjax=null) in the template. I tried turning it on (mathjax="default") and then rmarkdown complains

#> Warning message:
#> MathJax doesn't work with self_contained when not using the rmarkdown "default" template. 

There's this closed issue in rmarkdown that suggests it should be possible to work around the default template limitation. One solution could be to start blastula template from "default" and subsequently modify it into the form envisaged by the package. I tried supplying the "default" template argument, but of course I just get an unreadable wall of text instead of an email.

Did you ever look into what it would take to enable mathjax in blastula? Can we at least catch the equation tags, created by $mathjax$ and change the font to Serif?