e·pis·to·lar·y 
/əˈpistəˌlerē/
adjective
adjective: epistolary
(of a literary work) in the form of letters.
“an epistolary novel”
LITERARY
relating to the writing of letters.
Origin
mid 17th century: from French épistolaire or Latin epistolaris, from epistola (see epistle).
Electronic “documents” such as recordings and radio, blogs, and e-mails are also forms of epistolary writing.
What is an Educational Epistolary?
An expert in education who writes letters and blogs, records videos and radio segments, creates ebooks and ecourses, and emails.
