Prisons in every state have a different policy. The policies in every prison vary. The person you are trying to reach will need to have the information you are looking for or you will need to request it from the office. This is one of many ways of locating whether or not you can contact a person by an email.
Go to the prison and request for the email address of the inmate. Most inmates will have identification numbers that may be required. Make sure you have all required information that will allow you to receive the email. Some prisons require you to be on the friend list for information, significant partner, and immediate family. It is always good to speak to the inmate first for information regarding his/her rights for you to request their email if they are allowed to have one. Ask your inmate to ask his/her lawyer to receive this information if you are unable to get the clerk to cooperate. You can go on to a search engine and find office phone numbers, emails and addresses for the front desk for assistance.
Speak to the front desk clerk allow them time to give you their policies on what you can write or cannot write in submission of your written correspondences. It is good to have them copy your rights as an inmate visitor who is writing the inmate. Of course, the clerk may forget to give you detail information on what is allowed, so ask questions, extensively like can you send photos, what kind of photos, how many emails can you send, is there a limit. After speaking with the clerk if you are satisfied, proceed from there, and use the email address accordingly. Otherwise, seek legal counsel or check with other offices for direction.
Go to a prison locator's on the Internet if all fails. After trying to speak with clerks, inmate and lawyer, and you feel that information is not given according to policy or would like a change of policy speak to your legislature. Seek an organization that will assist you in contacting your inmate via email or mail. Keep contacting people requesting email information until you run out of options then resort to mailing your inmate. Some prisons are still behind times, so they may not honestly have that capability. The inmate would enjoy a letter regardless of the delivery, so go ahead and follow whatever procedures they require even if that excludes emailing.
Tip: Ask questions when talking to the clerk. They are the ones who can direct you if they do not have the information you need.
Warning: Do not rely on your inmate to know his rights or privileges when he/she is in prison. The best responses to your questions are usually done through your lawyer if you have one. Get your lawyer to do some work. If anyone can get the work done, it is someone with authority. Most prison clerks do not enjoy giving visitors information needed to visit their inmate. Weigh the consequences when speaking to a clerk, if possible check around.