Mail Fraud

Mail fraud occurs when the U.S. Mail is used in the furtherance of a criminal act. In order for a defendant to be convicted under 18 U.S.C. 1341 for committing mail fraud, the following elements must be satisfied:

• The defendant must have been engaged in a scheme to defraud.
• The scheme must have involved material misstatements or omissions.
• The scheme resulted, or would have resulted upon completion, in the loss of money, property, or honest services.
• The defendant must have used or caused the use of U.S. mail in the furtherance of the scheme to defraud.

Conviction of mail fraud will result in either a fine, imprisonment, or both.

Let's see. This was an organized, large scale effort to send letters which falsely claimed to be from the union, including the unauthorized use of the union's logo. This was sent with the intent to deceive, and to induce members to sign a request under false pretenses, including overt and intentional lies about what they were signing. The victims would face the potential loss of their union membership, and the union would lose the dues they would have collected. And they used the U.S. mail to carry out their scheme.

I'm not a lawyer, but that sounds like it hits all the requirements for mail fraud to me.