If they are in federal prison, you can email them for free but the inmate is charged by the system for the minutes they are on the email program whether reading incoming emails or writing outbound emails. The charges are deducted from their commissary account. The program is called Corrlinks.
For other prisons, there are no free services - there is always some form of charge whether it be on the side of the inmate or the side of the loved one on the outside.
https://www.inmateaid.com/ask-the-inmate/my-fiancee-said-something-about-being-able-to-email-him-for-free-how-do-i#answer
Accepted Answer Date Created: December 04,2015