Generally, no. Unmatched emails will not prevent those follow-ups from going out. However, you can choose to block follow-ups when you have unmatched emails by going to the project in question, and clicking the “Settings” button to the top of your screen and clicking “Project Settings” (Alternatively, you can access this screen when you are viewing the “Projects” screen and clicking on the “Settings” chrome wheel icon at the top right corner of the project in question).
Once in the “Project Settings” screen, you can click the blue “Advanced Options” to enable more settings to be shown. You will see a setting entitled “Block Follow-Ups.”