The following email was sent to the MIT community today from President L. Rafael Reif. To the members of the MIT community, I write on the eve of a day that holds tremendous meaning for many African Americans: Juneteenth. It marks the day in 1865 when the people held in slavery in Texas were finally told – two and a half years after the Emancipation Proclamation – that they were legally free. In honor of Juneteenth, many organizations in Greater Boston are offering free educational programming online, including the Royall…