Some servers build a message's preview from its HTML body without skipping
the <style> element, so a marketing mail's preview - in the list and in its
push notification - can read "@media screen and (min-width:600px){.hide{
display:none!important;…" and never reach the text.
Drop whole leading rules from the preview before showing it; a preview that
ends inside the style sheet was nothing but CSS and becomes empty, so the
usual "no preview" text shows instead. A rule only counts as CSS when its
block holds declarations or further rules, so prose with a brace in it
("the meeting is at {time} tomorrow") is left alone.
Clicking a new-mail notification opened `/mail/message/<id>` in
whichever account was active. With several accounts signed in, that
looked the id up in the wrong account: nothing opened, or a different
message did and was marked read.
The preview API now returns the cookie slot of the login that owns the
notified account, the service worker adds it to the permalink (or links
that account's Inbox for a group notification), and the app switches to
the login on that slot before opening the message.
Resolve the Inbox mailbox id before running Email/query.
The previous query passed a JMAP result reference object directly into the inMailbox filter, which can make the preview endpoint return 502 and cause push notifications to fall back to the generic “New mail” text.