recipient not receiving email

Fergusson1– wrote:

One person not receiving my emails even though have sent to same email address for last 4 years

What error message do you get?

Maybe you've introduced an error into their email address.

Maybe they have an email problem where your emails are auto sent to trash or spam.

Maybe their email provider has blocked you.

Try asking them to send you an email then reply to that email to see if they get your reply.

Try using your email provider's webmail interface to send an email to them.