Handle downed email server gracefully

[Alan Elkner]

We need to gracefully recover from the case where the email server is down at the time that we are sending an email. zope.sendmail does have queued mail delivery, meaning that undeliverable email does not get deleted, but rather remails stuck in the mail-queue/new directory until the stuck condition is unwound. However, that fact is certainly not obvious to the schooltool user, so we need a view that show what email is stuck.

[Alan Elkner (aelkner)]

If the email server is in fact down, we need to add an entry to the schooltool log, makeing sure that the new entry does in fact show up in the log interface from within schooltool.