Is this illegal or considered harassment

Lafayette Louisiana
After firing a manager he said not to contact him except by certified mail or he will sue. I emailed him about a problem he caused & he responded that he is contacting a lawyer & never answered my email. I was simply asking him why he ordered something that he was told not to order while he worked in the store. I know have the item and must pay for it because of this (no return allowed). If I email him again & ask him again about the issue is this against the law (bc he said not to contact him) & can he actually sue?

No, its not illegal for you to contact him, however, what makes you think that he is going to respond to your questions? What do you hope will be the outcome from you asking him a question by email?

Anybody can sue anyone for anything.

However, it's quite unlikely that he can SUCCESSFULLY sue you.

No, but he CAN successfully file harassment charges.