Sometimes emails go into the spam folder. This happens more frequently when you're a new sender in a new email service. One best practice to help your emails get into the inbox and avoid the spam folder is to ask subscribers to safelist your from/reply-to email address.
Safelisting essentially says, “This email address is someone I want to hear from” and safelisting an email address helps spam filters know that it is OK to deliver those emails to the inbox. Safelisting may require adding the sender’s from/reply-to address to your contacts list, as well as adjusting a security program filter.
Safelist an email address in a security filter
Security programs help protect users from unwanted email or viruses. Some security programs will block email from new senders. Safelisting the sender's from/reply-to address as well as the sender's IP address is usually the best way ensure emails make it to the inbox right away. Ask your IT team to help with these steps.
Example from Outlook 365
Safelist an email address in an email client
For most email clients, safelisting is as simple as adding the sender's from/reply-to address to the contacts list. In modern email clients like Gmail, Yahoo!, and AOL, you can hover over the sender's address and click Add to contacts. In Outlook desktop, you will go to Junk Email Preferences and add the address to safe senders. You may need to review help articles from the inbox provider to confirm that you have safelisted the email address correctly.
Example from Gmail