Complex sentence: The pamphlet was mailed to 520 of Italy's most powerful individuals and was received as genuine; however, after reprinting the tract into a small book, Sanguinetti revealed himself to be the true author.
Split into simpler sentences: The pamphlet was mailed to 520 of Italy's most powerful individuals. After reprinting the tract into a small book, Sanguinetti revealed himself to be the true author.