The message details panel built its received line, attachment summary
and spam score by gluing strings together; each is now one ICU message
(the attachment count is a proper plural). The SPF/DKIM/DMARC results
use the webmail's translated result names, and an invitation's date is
formatted in the app language instead of always in English.
The quick reply box wrote its own "date, name <email>:" quote header;
it now uses the composer's translated "On {date}, {from} wrote:" line
so both kinds of reply look the same.
The back button, the subject and header star buttons, the sender
avatar and the More/Tag sheet close buttons get screen reader labels,
and the screens i18n test covers the viewer files.
Linus Rath