I would suggest you to add an extra security, which is email ssl certificate to encrypt the email.

Comodo email certificate is free.

The email ssl certificate has to be installed in both the sender and recipient email client.

even though the scammer mimic your identity or fake your email, but without your ssl certificate installed on their device, your client will get non-encrypted email.

so they can be aware of it, since both of you have agreement to send encrypted email.

if your client did not install your ssl email certificate, they can't read the email you sent them, that's why I suggest you to use encrypted email.

Or you can consider SPF or PTR record.

btw, comodo ssl email certificate is not longer free now.