A person who writes epistles or is devoted to letter-writing as a form of literature or communication.
From epistle plus the suffix -arian (one who practices or is devoted to something), similar to words like vegetarian or grammarian. This emphasizes the person's dedication to epistolary writing.
A true epistolarian sees letter-writing as an art form—and history is full of them, from Seneca to Jane Austen to the Romantic poets who crafted letters as carefully as poetry.
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