Email itself is just a standard protocol; anyone can implement it. So, yes, there is a very low barrier to entry. Also, there are various problems around curren

Email itself is just a standard protocol; anyone can implement it. So, yes, there is a very low barrier to entry. Also, there are various problems around current email usage patterns that people want to solve: dealing with enormous inboxes, dealing with long conversation threads, managing contacts, integration with business workflows, etc.