With Collapsed Topics release 2.2.4.1 Quickmail works fine.

Upgrade to 2.2.6.4 and Quickmail breaks.

• The following Quickmail links result in an empty page: Compose, View Drafts, View History, Alternate Emails. Only the Configuration link works.
• All other blocks work fine, only Quickmail has problems.

This happens regardless of theme in use.

Change format from Collapsed Topic to Social, Topics, or Weeks and Quickmail works fine.

Roll back to top_coll 2.2.4.1 and Quickmail works again.

We tested this on various test installations including a fresh local install and repeatedly got this PHP error:

Notice: Undefined variable: DB in /Applications/MAMP/htdocs/moodle22/blocks/quickmail/config.php on line 14

Fatal error: Call to a member function get_record() on a non-object in /Applications/MAMP/htdocs/moodle22/blocks/quickmail/config.php on line 14