Using classic Outlook for Windows in business environments
Hello AlainBrunelle2,
Welcome to the Microsoft community.
May I know if you can send emails to Chinese companies via webmail instead of Outlook app?
In addition, according to your description, you want to send the email to a Chinese company, then it may be that this company has intercepted your email, which prevents you from sending it successfully.
And if you are sending email to China, it will be subjected to stricter email filtering than any other country in the world. This could result in email delays, delivered emails with unclickable links, or flat-out non-deliverability.
You can refer to this article to learn how to improve email deliverability to China.
Improve email deliverability to China (Dynamics 365 Marketing) | Microsoft Docs
We have to go through a series of steps to find the real cause of the problem. If you still have problems, please let me know and I will continue to help you with the problem.
Sincerely,
Mavis - MSFT | Microsoft Community Support Specialist