Address TECO staff by first name or last name?

If my TECO person signs the email with the first name, should I continue to address by their last name? E.g. keep saying “Ms. Lee”?

Sure, seems fine to me to err on the side of formality. I’ve noticed some of the TECO employees responding to me like that (where I sign with my first name but they address me more formally).

I guess Western conventions are fine, as TECO staff should at least be more international.

Just so you know though, in Chinese it is actually rude to refer someone by family name…

Correction, saying X先生 小姐 is fine but saying 姓X的 is rude.