Say it plainly before you say it cleverly
Idioms and figures of speech that feel natural in one region often confuse or mislead someone from another. "Let's touch base" or "circle back" are common enough to be safe, but more local expressions are worth swapping for plain, literal language when writing to an international audience.
Put dates, times and numbers in a format that can't be misread
"05/06" means two different dates depending on the country reading it. Writing "5 June" or "June 5" removes the ambiguity entirely. The same care applies to time zones — always name the zone, don't assume it's understood.
Confirm understanding explicitly, both ways
In cross-cultural conversations, a client saying "okay" doesn't always mean full agreement — in some cultures it can simply mean "I heard you." Confirming specifically — "so to confirm, we'll proceed with option B" — closes that gap in both directions.
Match formality to the client's own tone, not your default
Some clients prefer brisk, informal exchanges; others expect more formal address throughout. Reading and matching their opening emails — rather than defaulting to one fixed style — signals attentiveness that clients notice, even if they don't mention it.