Email deliverability determines whether your messages reach the inbox or get filtered as spam. Understanding and optimizing these key factors can significantly improve your email performance:

Sender Reputation

Like a credit score for your email address, mailbox providers track your sending history. Factors affecting reputation include:
Spam complaint rates (keep below 0.1%)
Bounce rates (maintain under 3%)
Consistent sending volume (avoid sudden spikes)

Authentication

SPF, DKIM, and DMARC act as digital ID checks, proving you own the sending domain. Without any of these authentications, your emails may be marked as spam.

Content Quality
Even authenticated emails get filtered if the content appears spammy.
Avoid trigger words (“Free,” “Big Win”)
Balance text-to-image ratio (30% images max)
Mobile-optimize designs (60%+ opens occur on phones)

Segmentation & Engagement

Sending relevant content to subscriber groups and preventing spam flags from disinterested recipients.
Example: Segment by purchase history or geographic location.
Performance Monitoring
Track these metrics promptly:
✅ Open rates
✅ Click-through rates
✅ Bounce rates
✅ Spam complaints

Deliverability isn’t luck, it’s science. By mastering reputation, authentication, content, segmentation, and analytics, you’ll consistently reach inboxes and drive real business results.