Is Yahoo not satisfied?

Yahoo China launched an infinite number of yahoo.cn mailboxes a few days ago. Yahoo and Yahoo do not want to say anything about this, because I have never used Yahoo's mailbox and have no right to speak.
Today, I registered a yahoo.com.cn mailbox to help my friends solve the problem. I wrote a little bit of temporary experience, only involving Yahoo Mail's "email filter" function.
This friend wants to use the Yahoo Mail Filter to automatically classify received emails and automatically transfer different types of job resumes to the corresponding directories Based on the subject Keywords of the emails. This requirement should be very simple, and all current mailboxes have this function.
Open the filter page in mailbox settings. You can set 15 filters. The specific setting steps are not mentioned, and the operation is relatively simple. The conditions I set are:

If...
The topic includes "Web development engineers"
Then...
Move emails to the R & D folder

Then, a test email is sent, which is displayed in the default inbox after receiving the email.

Is there a problem with condition settings? The test email sent more than a dozen emails and finally found the cause of the problem.
When Yahoo filter filters and determines the mail subject, if the filter keyword contains Chinese characters, the matching result will fail. That is to say, if the filter keyword is set to Chinese, the topic filter is invalid at all!
Body filtering can recognize Chinese characters normally, but the emails received by my friend can only be identified by the subject, but cannot be identified by the body of the email.
Alas, speechless ~~~
Yahoo!ProgramOr is the Yahoo engine used directly ???
Finally, my advice to that friend is:
1. Wait for Yahoo to fix this problem
2. Change other email addresses
3. Do not change your mailbox. Use Foxmail or outlook to receive and filter emails.

Finally, I chose 3 and installed Foxmail to solve the problem of automatic mail filtering.