This reverts commit 3e9e97e6, reversing
changes made to 0d931107.

Until https://github.com/django-ses/django-ses/issues/137 is resolved, we need
to proactively search for and prevent unicode values in from_addr.

EDUCATOR-1773

Add the course root to the bulk email template context so that templates can customize the full course URL with a custom hostname.

instead of constructing it from settings.HTTPS and settings.SITE_NAME

and adds system tests for affected methods.

2. Add site configuration overrides to theming/helpers.py
3. Move microsite.get_value from theming/helpers to site_configuration/helpers
4. Move microsite_configuration.microsite.get_value usages to site_configuration.helpers.values

This code will be hit if, during a retry of the send_email task, an error
is encountered that means we need to retry the task again. Since the task will
be retried with timed backoff up to predefinied limits, this is an expected
situation and does not need to be logged as an exception.

Adds cohorts as valid bulk email targets.

TNL-4356

Allows multiple bulk email targets to be specified at once.

-The previous "All" option has been split into "Staff" and "Learners"
-The backend changes made here lay the groundwork for cohort emailing
-The data migration, 0005, is somewhat large and requires deploy attention
-Tests have been updated
-Numerous safe-commit-linter fixes are included

* truncate email from addresses if >320 chars when encoded (TNL-4264)

* use exact lengths

clean up and fix quality violations

since get_course can never return None, we can remove these lines

clean up and fix quality violations

since get_course can never return None, we can remove these lines

TNL-2677

TNL-1877

TNL-1877

When celery runs in eager mode, there is a bug and an exception
is not thrown when using retry logic. A PR to fix the bug can
be found here: https://github.com/celery/celery/pull/2607

In the mean time, we have to deal with the fact that in eager mode
celery will not throw the exception but simply return it. So we
raise it ourselves.

This reverts commit 228cca4e38ec79f5cbb54098c788ab9556f602e2.

This reverts commit c2e5bd3d.