It looks like images don't display with messages sent out via the 5 minutes cron schedule. When viewing the image info it shows as "Unknown (not cached)". Emails sent immediately after registration to the admin and the user, however, do show the images as they should (see attached images).
Happens in 1.3.1 and 1.3.2
Happens in 1.3.1 and 1.3.2