My mailbox receives users forms doesn't show users' email address in the forms

Hello,

There is a troublesome problem that i need your help.
As my subject, recently my mailbox receives users forms doesn’t show users’ email address in the forms which users submitted forms on my website like contact form and subscriber forms, however it shows email address only if users left their email address with *****@qq.com otherwise it won’t show in my form received.
so can you help me to check what is the reseason and try to help? Thank you very much!

Regards,