There are multiple reasons why an email might not be delivered:
Spam Filters: Emails can be filtered out as spam if they contain certain keywords, excessive links, or suspicious attachments. Sender Reputation: If your sending domain or IP address has a poor reputation, it is more likely to be blacklisted by ISPs. Technical Issues: Issues like improper DNS settings, lack of SPF, DKIM, or DMARC records can hinder email delivery. Recipient Issues: The recipient's inbox might be full, or their email address might be invalid.