This is to acknowledged receipt of your email
A classic!
"This is to acknowledge receipt of your email" is a common phrase used to confirm that an email has been received and read. It's a polite way to show that you've taken the time to read the sender's email and are acknowledging its receipt.
Here's a more formal version:
"This email is to confirm receipt of your email dated [date] with the subject [subject]. We have received and reviewed your message and will respond accordingly."
And here's a more casual version:
"Thanks for reaching out! Just wanted to let you know that I've received your email and will get back to you soon."