how to find out e mail i send are open by recepand

What you are asking is for a "read receipt" which is a simple command in Outlook and other email services. It should be a simple checkbox but I don't see that's it's available in Apple mail. I find them useful and didn't find them to deter others from opening mail if we know each other. It's often important to know if someone has read something! That's why we have that feature on texts, right? Good to know info.

It is possible to send a Read Receipt but almost nobody would reply to them.

reiko48 wrote:

how to find out the email I send is an operand

Ask the recipient to let you know when they open the email you sent them. Don't expect many responses.