Good evening Dion and welcome back!
Thank you for reaching out to us.
We are sorry to hear about your RSVP confirmations being labeled as from WordPress.
We will gladly try to assist you on this topic.
It sounds like the RSVP plugin is using the default WordPress mail functions. The easiest way to solve this would be through the use of a SMTP plugin that would let you replace the default WordPress mail functions.
There are a good number of them out there, but from experience, I’ve had great success with Easy WP SMTP.
Let me know if that helps.
Have a great day!
Geoff B.