Special character displayed as "?"


I have some Czech friends with some special characters in their names. Such like “Tomáš”.
But in eM Client, in the and from: , it’s displayed as "Tomá?"

I’ve tried changed different fonts, but it didn’t help.

I’m using eM Client Version 7.1.33101.0 on Win10. The local language of my PC is simplified Chinese.

Thank you in advance for your help.