Your system side

- List hygiene
• Responding instantly to unsubs
• Optin confirmation strategy
• Removing or suppressing the unengaged
• Removing hard bounces immediately
• Removing soft bounces after the 3rd bounce • Master suppression list
- Engagement monitoring
- DKIM and SPF
- Properly formatted HTML
- Careful wording selection (spam assassin)
- Equal image to text ratio
- Monitoring abuse@ and postmaster@ addresses
- Volume and consistency
- Obey the law (can spam act)

Off your system factors
- Blacklists
- Accreditation programs
- ISP feedback loops
- ISP whitelisting