In National Labor Relations Board v. Blue Bell Inc., 219 F.2d 796 (4) (5 Cir. 1955) a female employee wrote a letter to employer's vice-president calling him a "liar".
In Maryland Drydock Co. v. NLRB, 183 F.2d 538, 539 (4th Cir. 1950), we held that an employer was entitled to maintain discipline by prohibiting "defamatory and insulting statements which reasonably tend to destroy such discipline....