I was jealous of Mail.app's ability to quick send messages to Things 3 since I hate the built in app and love Outlook for Mac. So I created this macro which uses CulturedCode's new mail-to feature.
It takes the message, prompts you for the actual to-do text (which gets inputted into the subject line) and automatically sends to your Things inbox.
You'll need to update the first "Insert by pasting" field with your unique mail-to address.
Forward Outlook to Things 3.kmmacros (4.1 KB)