If your emails land in spam, nothing else matters. This guide covers everything you need to know about deliverability in 2025.
The Three Pillars of Email Authentication
SPF (Sender Policy Framework)
SPF tells receiving servers which IP addresses are allowed to send email on behalf of your domain. Without it, anyone could spoof your domain.
How to set it up: Add a TXT record to your DNS: v=spf1 include:_spf.google.com ~all
DKIM (DomainKeys Identified Mail)
DKIM adds a digital signature to your emails, proving they weren't tampered with in transit.
Setup: Generate a DKIM key in your email provider, then add the public key as a TXT record in your DNS.
DMARC (Domain-based Message Authentication)
DMARC tells receiving servers what to do if SPF or DKIM fails. Start with monitoring mode: v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com
Warming Up New Email Accounts
Never blast hundreds of emails from a fresh account. Here's the ramp:
- **Week 1:** 10-20 emails/day, mostly to people who will reply
- **Week 2:** 30-40 emails/day
- **Week 3:** 50-75 emails/day
- **Week 4+:** Gradually increase to your target volume
Use a warmup service to automate sending and replying between real inboxes.
Maintaining Good Reputation
Do:
- Keep bounce rate under 2%
- Maintain reply rates above 5%
- Remove unengaged contacts regularly
- Use multiple sending domains for high volume
Don't:
- Send to purchased lists
- Ignore unsubscribe requests
- Use URL shorteners (they look spammy)
- Include too many links or images
Monitoring Your Reputation
Check these regularly:
- [Google Postmaster Tools](https://postmaster.google.com) (for Gmail delivery)
- [Microsoft SNDS](https://sendersupport.olc.protection.outlook.com/snds/) (for Outlook)
- [MXToolbox blacklist check](https://mxtoolbox.com/blacklists.aspx)
- Your ESP's bounce and complaint rates
Good deliverability isn't a one-time setup - it's ongoing maintenance.