The email is built from the individual messages that are approved
either for publication or foreshadowing (i.e. to be put in the
Upcoming section).

The email message is created by a PHP script. There are actually 4
versions of the email, one per audience. 

For a given date, the first step is to create entries in the email
contents table that link messages to a given email. As messages are
linked in the email contents table each messages published or
foreshadowed flag is set as appropriate.

From the email contents the actual email is built. The email consists
of 3 sections

1. the headlines, grouped by category
2. the upcoming things
3. the categories, with full messages and links as appropriate

During creation each of these sections is created separately and for
each audience (e.g. a headlines, body, and upcoming hashes, each with
entries for students, faculty, staff, and other).

The appropriate sections are then stitched together, along with a
universal header and footer, and sent to the appropriate email list.

Finally, all rejected messages are deleted. (NOTE: possibly all
rejected messages older than X days are deleted).
