The inmates do not need an account, they will receive the mail in 2-3 business days but delays often happen as the staff decides when the mail is handed out
https://www.inmateaid.com/ask-the-inmate/how-long-does-it-take-the-inmate-to-receive-your-letter-or-post-cards-from.amp#answer
Accepted Answer Date Created: January 15,2016