As part of the 2.7 release, we have tried to fix the email deck not working bug. It is not working due to a sandboxing issue (see for an explanation) with Decked Builder interacting with the Mail app.

In essence, Apple generally forbids sandboxed apps (basically all apps from the App Store) from interacting with other programs.

We have requested entitlements from Apple for Decked Builder to be able to send decks by email, so we should hopefully have this resolved for the next 2.7 patch.