The UX spec would like quotation marks around the {{ subject }} part. I am a bit puzzled though as your screen shot seems to show correctly some quotes around the subject. 

UX also asked if we could use the curly quotation marks instead of the straight quote. Hopefully this comes through:

    {{ from }} “{{ subject }}”

So, the two quotation marks are the following (taken from this [wikipedia page](http://en.wikipedia.org/wiki/Quotation_mark_glyphs#Quotation_marks_in_Unicode)):

“ 	U+201C 	left double quotation mark 	&ldquo; 	Double curved quote, or "curly quote", left
” 	U+201D 	right double quotation mark 	&rdquo; 	Double curved quote, right

I would also favor calling this l10n key `new-emails-notify-multiple-accounts-body` as it is easier for me to distinguish from the other key for the subject part.