Note there are two very different classes of volume/priority/urgency/required deliverability:
- campaign / marketing / newsletter delivery
- non-campaign / transactional / alerts / updates / password changes
This page is currently oriented to SMTP relay / smarthost providers for transactional email delivery.
- Spamassassin: Avoiding False Positive (For Senders)
- Email Deliverability & You (And Your Startup)
- Deliverability.com - group blog from the email deliverability community