Between the sender and the subject line, this is all one needs to know in many cases. It's preferable that they do not open the email, because in previous instances, simply opening an email triggered the exploitation of a vulnerability: https://learn.microsoft.com/en-us/security-updates/SecurityB...

I report nearly all auto-generated unsolicited emails as spam. I also report nearly all follow ups to ignored cold emails. I will protect my inbox.

Thank you for response, I also find some tips here https://designmodo.com/email-subject-lines/