Popular email clients like Gmail will automatically linkify link-like
content present in an HTML email they receive, even if it doesn't have
links in it. This made it possible to include what in Gmail will be a
user-controlled link in invitation emails that Zulip sends, which a
spammer/phisher could try to take advantage of to send really bad spam
(the limitation of having the rest of the invitation email HTML there
makes it hard to do something compelling here).
We close this opportunity by structuring our emails to always show the
user's name inside an existing link, so that Gmail won't do new
linkification, and add a test to help ensure we don't remove this
structure in a future design change.
Co-authored-by: Anders Kaseorg <andersk@mit.edu>
The alt text of the leading images were displayed as preview
content in inbox by email clients like gmail. Since the leading
images were used mostly for decoration this made the preview
content gibberish. It's fine to set the alt attributes to empty
from accessibility point of view since the old alt attributes
did't added any meaningful information.