recieved an email that my find my phone has been disabled it has not

I am basing my response on two data points that you have confirmed in your post.

1. Find My is ON in the settings of your iPhone.
2. You stated that the email that you received is legit.

Did you recently sell, giveaway or trade in your iPhone? If YES, then that email may be referring to your previous iPhone.

If you are certain that the email is legit, then there may be an issue with the connection between your iPhone and Apple's server. You can toggle Find My OFF and then back to ON in Settings ➔ Apple ID (Your Name at Top) ➔ Find My ➔ Find My iPhone.

Axel F.

Additionally … if you determine the email to indeed be fraudulent … you should forward the e-mail - as an ATTACHMENT - to Apple:

reportphishing@apple.com

Ref: https://support.apple.com/en-us/HT204759

It's most likely a scam email designed to get you to divulge personal information. Do not respond to it or give any information.