This type of error occurs when your followup tries to use a service that is not yet set up or that is not yet included in your plan. For example, if you send a message to firstname.lastname@example.org but your phone is not yet set up, we send back an error email (yet still schedule the followup).
If you’re not sure why you keep receiving these error messages, check your default flags setting (which automatically adds flags to every message), or make sure your email client is not auto-completing addresses with flags in them.
Ugly Text Error Messages
Our attachment size limit is currently 15M. If an attachment exceeds this, the software we use to receive our email throws an error directly. Unfortunately it’s not very pretty. For this we apologize. It’s a known issue that we’ll be working on in the near future.