Dedicated IPs and proper SPF, DKIM, DMARC improve deliverability. Avoid shared IPs with bad senders. Warm up new IPs gradually. Many teams use a transactional email service instead of self-hosting to reduce complexity.
Deliverability basics
- SPF: DNS record listing servers allowed to send for your domain. Reduces spoofing and helps inbox placement.
- DKIM: Sign messages so receivers can verify they came from you. Reduces spoofing and improves trust.
- DMARC: Policy (in DNS) telling receivers what to do with messages that fail SPF/DKIM (reject, quarantine, or allow). Start with monitoring (p=none) then tighten.
IP reputation
- Dedicated IP: Your sending IP is not shared with unknown senders; you control reputation. Warm up gradually (low volume at first).
- Shared IP: Cheaper but reputation is shared; one bad sender can affect everyone. Avoid for critical or high-volume sending.
- Warm-up: New IPs need to build reputation; increase volume slowly over days or weeks to avoid spam filters.
Self-host vs transactional service
- Self-host: Full control; you manage postfix/exim, bounces, blacklists, and reputation. More work and expertise needed.
- Transactional service (SendGrid, Mailgun, etc.): They handle reputation, deliverability, and scaling. Good for app emails (signup, password reset, notifications). Often better deliverability with less ops.
Summary
Use SPF, DKIM, DMARC; prefer dedicated IPs and warm them up. For app emails, a transactional service often beats self-hosting on deliverability and simplicity.
