ScheduledJob was written for much more generality than it ended up being
used for. Currently it is used by send_future_email, and nothing
else. Tailoring the model to emails in particular will make it easier to do
things like selectively clear emails when people unsubscribe from particular
email types, or seamlessly handle using the same email on multiple realms.
This commit is a step towards the goal of replacing most of the
send_future_email pathway with a call to send_email.
Note that this commit changes the default value of sender from "Zulip
<NOREPLY_EMAIL_ADDRESS>" to "NOREPLY_EMAIL_ADDRESS". NOREPLY_EMAIL_ADDRESS
will soon be changed to have the Zulip in front.
datetime.utcnow() is a timezone-naive datetime. The Django ORM interprets it
in the settings.TIME_ZONE timezone (e.g. 'America/New_York' in the
development server). We perhaps haven't noticed errors yet since with
'America/New_York' all it means is that emails are sent 5 hours early, or a
slightly different set of messages are included in the digest.
This command should be run continuously via supervisor. It periodically
checks for new email messages to send, and then sends them. This is for
sending email that you've queued via the Email table, instead of mandrill
(as is the case for our localserver/development deploys).
(imported from commit a2295e97b70a54ba99d145d79333ec76b050b291)