1. Make sure you use a shamrock emoji ☘️, not a four leaf clover 🍀

Per google :

"On St. Patrick's Day, shamrocks are a prominent symbol, representing the Holy Trinity and Irish culture, and are often worn or used in decorations."

2. It's St. Patrick's Day, Patrick's Day, Paddy's Day, even St. Paddy's Day. It is never Patty's day or St. Patty's Day. Never ever. Nope.

☘️ Happy St. Paddy's Day! ☘️

( There's a good chance your Irish colleagues have avoided telling you this before now because honestly, the most Irish thing to celebrate is actually avoiding awkward social situations at all costs. )