HI Mike,
The decision to send the email to your spam folder is made by your email server, based on the "reputation" of the sender (sender and reply-to addresses). The anti-spam and anti-virus programs work to try and identify mail you don't want to see.
Your Moodle server will have an IP address that maybe does not have a good reputation, and you can check it here:
https://talosintelligence.com
You may need to talk to the person who administers your email server and get the IPAddress and/ or sender email address whitelisted.
You can also check the email message headers to see if there is any indication for the reason why it was placed in the spam folder. Most systems log the reason with an entry there.
Good luck.
Gary