Business formality varies more than language does

Two companies that both write in English can have very different norms around emoji — some startup cultures use them freely in Slack and email alike, while more traditional or hierarchical business cultures expect a formal, emoji-free tone by default.

Reading your counterpart's lead

The safest approach in a new international business relationship is to mirror the other side's tone: if their first email is emoji-free and formal, stay that way; if they've already used a friendly emoji themselves, it's generally fine to respond in kind.

Where a single emoji still helps

A checkmark or thumbs up in a quick confirmation message ('Received, thanks ✅') reads as efficient rather than unprofessional in most business cultures, since it's functional rather than purely decorative.

What to avoid entirely

Skin-tone modifiers, slang-heavy emoji, and anything with a culturally specific meaning are best avoided in first-contact or high-stakes international correspondence, where the safest set is a small handful of universally understood symbols.