What are the ramifications of letting an old domain that was used for email go back into the market?

I own a .net domain but recently I was able to get the domain that I originally wanted to own. I wanted move over to the new domain for my email which was the only thing I was using my .net domain for.

I only had two email under that .net domain which is just for looking for work and my personal for "buying" games.

What are the ramifications of letting someone else own my domain in the future? (Mostly talking about email)