To improve the chances that emails from your domain are delivered to Gmail inboxes and not marked as spam, it is recommended to follow the following best practices:
- Set up valid reverse DNS records for your IP addresses that point to your domain.
- Align your SPF and DKIM records.
- Use the same domain to send emails and host your website, and set up SPF and DKIM for this domain.
- If possible, send all emails from the same IP address. If you must send from multiple IP addresses, use a different IP address for each type of message (e.g., separate IP addresses for account notifications and promotional messages).
- Don't combine different types of content in the same message.
- Use the same From email address for messages of the same category.
- Regularly check that your domain is not listed as unsafe with Google Safe Browsing.
- Do not send test phishing messages or test campaigns from your domain.
- Do not impersonate other domains or senders without permission.
- Messages from addresses in the recipient's Contacts list are less likely to be marked as spam.
- If a legitimate message is marked as spam, the recipient can mark it as not spam to ensure future messages from the sender are delivered to their inbox.