to offer the words of sympathy about the Belgium bus crush in Swiss Apls

[Olympias]

It's probably not the best place on MN for my question, but ...
I interact via email with a client based in Belgium almost on a daily
basis. Is it appropriate to send an email saying how sorry I was to hear about the crush where 28 people died? I don't know if any of his relatives or friends are affected (his own kids are small).

I forgot to add that he hasn't been in touch for a couple of days. Come to think of it, haven't heard from him since the day of the crush.

crash, not crush, of course

Totally appropriate and very thoughtful.