Yes it does. It works with most Bluetooth equipment.
Speaking Email works with Bluetooth speakers using Bluetooth Audio (A2DP) profile.
It also works with a microphone and speaker using Bluetooth Hands-Free Profile (HFP), which is what cars use for making phone calls.
Speaking Email switches between audio outputs automatically to get the best quality output. When enabling the microphone Speaking Email will automatically switch from A2DP to HFP, (and you will notice a drop in sound output quality).
You should set up your phone to play audio to a bluetooth output such as your car stereo, or bluetooth headset / earphones. You might need to check your device documentation / car manual to see how to complete a bluetooth pairing. Once you have paired your phone with the car stereo or other bluetooth device, do a quick test - for example, play music or a youtube video on your phone, and make sure you can hear the sound through the car speakers.
Check the volume slider and mute button. Once that happens, Speaking Email will just speak normally through your bluetooth paired connection.
If you have problems, go into your phone's Bluetooth, remove the connection and re-pair it. That seems to solve 90% of issues.
Force quitting Speaking Email, turning off the phone and Bluetooth speaker and starting again can also help.