Why Your Marketing Emails Land in Spam — and How to Fix It
Deliverability problems usually aren't about your content. Three technical records and one list-hygiene habit fix most of it.
When a campaign's open rate suddenly drops, the instinct is to blame subject lines. In practice, most deliverability problems trace back to missing authentication records or a decaying contact list — both fixable, and both things your email marketing tool can help diagnose if you know where to look.
Start with authentication: SPF, DKIM, and DMARC
Major mailbox providers now effectively require bulk senders to authenticate their domain with SPF, DKIM, and DMARC records. Every mainstream email marketing platform has a domain authentication page that generates the exact DNS records to add — if you've never completed that setup and you're sending from your own domain, this is almost certainly your biggest problem.
After adding the records, use your platform's verification check and send a test to accounts at a few major providers. Authentication failures are visible in the message headers if you want to confirm the fix directly.
List decay quietly poisons your sender reputation
Addresses go stale: people change jobs, abandon inboxes, and old addresses get converted into spam traps. Repeatedly mailing dead addresses raises your bounce rate and tells mailbox providers your list is low quality. Pruning contacts who haven't opened anything in six to twelve months typically improves deliverability more than any content change.
Sudden volume spikes look like spam, because they usually are
Jumping from a few hundred emails a month to tens of thousands overnight is a classic spam pattern, and providers throttle it. If you're moving to a bigger list or a new sending domain, ramp volume gradually over a few weeks so your sending reputation can keep up.
- Complete SPF, DKIM, and DMARC setup in your email platform's domain settings — this is the highest-impact fix
- Prune or re-confirm contacts with no opens in 6–12 months
- Ramp up sending volume gradually after list growth or a domain change
- Watch bounce rate per campaign — a rising trend is an early warning, not noise
Maya Oduya
Staff Writer, Security & Privacy
Maya covers security and privacy tools, focusing on how encryption and access-control claims translate into real day-to-day protection rather than marketing language.
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