Make sure DNS records are set for your sending email domain for:
- SPF
- DMARC
- DKIM
EasyDMARC has free tools to help you with these records.
Always send email from the sending domain you have set up in HighLevel, and ensure that your email does not include words, phrases, and punctuation that would trigger it as spam.
Monitor the health of the email account through which you are sending the email (Google Workspace, Outlook, etc.). If the sending email service is using a blacklist IP address, for example, your email may be:
- Totally rejected by email servers. In this case, the email will never reach the email account you are sending it to.
- Flagged as spam. In this case, it may make it to the email account you are sending it to, but probably put into their spam folder.
Also see this HighLevel tutorial: Why Are My Emails Going To Spam?