Thought I should share this workflow to search Mail.app
Use the following keywords to search:
emfrom to search the sender's name and email address
em for a general subject + content search
emsubj to search specifically for a subject line
You can download it here. Enjoy!
This version is suitable for both Alfred 3 and Alfred 4.
Compatible with macOS versions up to Mojave. Unfortunately, due to some changes made by Apple in macOS