On their Foundry blog:

The National Organization for Marriage recently announced the launch of a new project called the Marriage Anti-Defamation Alliance. This vital project responds to growing concerns about the reprisals directed against many people who support marriage as one man and one woman.

The Heritage Foundation has documented, for example, how people who supported Proposition 8, the California marriage amendment, were “subjected to harassment, intimidation, vandalism, racial scapegoating, blacklisting, loss of employment, economic hardships, angry protests, violence, at least one death threat, and gross expressions of anti-religious bigotry.”