# Keep emails out of spam

> The authentication, content balance and trust signals that keep your campaigns in the inbox, not the junk folder.

Source: https://www.kualo.com/knowledgebase/senders-deliverability/keep-emails-out-of-spam
Updated: 2026-06-10

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Several things can send your email to the junk folder instead of the inbox. The good news is they're mostly within your control. This guide covers the big ones: authentication, content, and the habits that build trust with inbox providers.

## Authenticate your sending domain

Authentication is the single most important factor. It proves to Gmail, Outlook and the rest that you're genuinely you and allowed to send from your domain. Without it, providers can't tell you apart from a spammer, so they send you to spam or block you outright - by some estimates, 60-90% of unauthenticated mail never reaches the inbox, however good the content. It also stops bad actors impersonating your brand. In short, authentication is the foundation that makes everything else work. See **[Authenticate your sending domain](/knowledgebase/senders-deliverability/authenticating-my-domain-with-spf-dkim-and-dmarc-protocols)**.

## Watch your content

**Avoid spam-trigger words** - go easy on "Free!", gambling terms, ALL CAPS and rows of exclamation marks.

**Balance images and text:**

- Keep images to no more than about 40% of the email.
- Keep text to at least 60%, with at least 400 characters.
- Don't tile images edge to edge, and give every image clear alt text.

By law, every email needs some text - even a simple "hello". A good image-to-text balance keeps you out of spam, encourages images to display, and helps your email load.

## Build trust

- Use a double opt-in signup.
- Test your own signup process and see where the email lands.
- Ask recipients to add you to their address book or safe-sender list.
- Encourage them to choose "always display images from this sender" - it marks you as trusted.

## Troubleshooting

**Still going to spam despite all this** - check your reputation with tools like Google Postmaster or Microsoft SNDS, double-check SPF, DKIM and DMARC, review recent complaint and bounce rates, and warm up with smaller engaged segments.

**Recipients report spam despite subscribing** - revisit your signup so expectations are clear, make sure your frequency matches what you promised, and consider a preference centre so people choose what they get.

**Different providers treat you differently** - test across providers before sending, watch delivery by domain, and build reputation gradually with each.

If you're doing everything right and still landing in spam, [open a support ticket](/knowledgebase/getting-started/how-to-create-a-support-ticket-in-mykualo).

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_Source: Kualo Knowledgebase — https://www.kualo.com/knowledgebase/senders-deliverability/keep-emails-out-of-spam · © Kualo Ltd._