Your Email is Unsecure!
A couple years ago my accountant sent me an email that contained my social security number. I was very upset with him.
I've had customers who want to order a Survival Still send me credit cards via email. I politely mention to them that they should not do this.
As this article demonstrates, email is NOT secure. Don't send anything sensitive via email. Don't send passwords, social security numbers, credit card numbers or even messages of a highly personal nature that you wouldn't want anyone else to read.
Now, to be clear, there are secure email options. I recommend ProtonMail. ProtonMail is end-to-end encrypted IF the recipient is also using ProtonMail. Plus, they give you the option to encrypt all email messages regardless of what service the recipient is using, but there are extra steps involved.