One of the most important parts of the prison detention, that the convict can not communicate, or only on very limited ways (like once in a month can meet his family or so). Sometimes there are same semi-legal, or illegal, but not strictly enforced ways of communication (like on phones smuggled in, typically by bribing the guards to see elsewhere). It is highly dependent on the country and on the case. But that a convict can openly send Instagram posts, is unthinkable. A typical convict is happy if he can talk sometimes to his family on a smuggled phone.
It is because prisons are optimized for these:
- To keep the convicts inside.
- To minimize their maintenance costs (the salary of the guards).
Keeping things out (mostly: drugs and phones), is only the third in the line.
However, Navalny is in a top security prison in Russia, and it is very likely, that in his case, the highest level of the prison officials are closely watching him. Probably even the highest level of the state officials (Putin).
So, how can Navalny send posts to the Instagram without the approval of the prison officials? Or, if the State allows him this freedom, why?