Email deliverability: avoiding spam (SPF, DKIM, DMARC)

You crafted your subject line, wrote relevant content, segmented your list — and yet your emails still land in junk. Deliverability is the discipline that decides whether a message reaches the inbox or not. It almost never depends on a single factor: it is the combination of your domain authentication, your sender reputation, your list quality and your content. This guide gives you the concrete levers to avoid spam.

Why emails land in spam

Mailbox providers (Gmail, Outlook, Yahoo) apply filters that evaluate hundreds of signals on every send. Three broad families of problems account for most spam placements:

• Unverified identity: without authentication, the filter cannot confirm you are really the declared sender — typical spammer behaviour.
• Bad reputation: too many complaints, bounces or sends to inactive addresses erode the trust providers grant your domain.
• Suspicious content signals: an unbalanced text-to-image ratio, trigger words, shady links or a missing unsubscribe link.

Authenticating your domain: SPF, DKIM, DMARC

Domain authentication is the foundation of all deliverability. It relies on three DNS records that prove to providers that your emails are legitimate. Since 2024, Gmail and Yahoo require them for senders at volume.

In practice, you start with SPF and DKIM, then deploy DMARC in none policy to observe the reports, before gradually tightening to quarantine and then reject. This is precisely the step where manual configuration blocks most users: you have to edit your domain's DNS zone and paste in the right values. SendAtelier guides you step by step to configure your sending domain (the exact DNS records to add, with verification that they have propagated).

Protecting your sender reputation

Once authentication is in place, providers build a reputation for your domain and IP as you send. Several factors push it up or down:

• Engagement: opens, clicks and replies signal wanted messages.
• Complaints: every "report as spam" click weighs heavily; aim for a complaint rate below 0.1%.
• Bounces: too many invalid addresses indicate a poorly maintained list.
• Consistency: regular sends beat isolated spikes followed by long silences.

Warm-up: scaling volume gradually

A new domain or IP has no reputation. If you send 50,000 emails out of the gate, filters react with suspicion. Warm-up means increasing volume in stages over two to four weeks, starting with your most engaged contacts (recent customers, active subscribers). You build a positive history that protects your future campaigns.

List quality

No technical optimisation makes up for a bad list. The two fundamental rules:

• Opt-in only: send only to contacts who have explicitly consented. Bought or scraped lists destroy a reputation in just a few sends.
• Bounce cleaning: automatically remove addresses that bounce (hard bounces) and long-term inactives. A smaller, engaged list delivers better than a large dead one.

Consent management and bounce tracking are natively tied to the CRM in MarketingAtelier: a contact who unsubscribes or bounces is automatically excluded from the next sends, with no manual work.

Email content

The message itself sends signals. A few simple rules sharply reduce the risk of spam:

• Balanced text-to-image ratio: an email made entirely of one large image is suspicious. Keep real, structured text.
• Avoid trigger words: "free", "win", "urgent", overuse of capitals and exclamation marks raise the spam score.
• Visible unsubscribe link: it is mandatory and expected by filters. An easy unsubscribe beats a complaint.
• Clean links: use a domain consistent with the sender, avoid generic URL shorteners.

On the MailAtelier side, every email goes through a deliverability audit before sending: more than 20 automatic checks (authentication, text-to-image ratio, trigger words, presence of the unsubscribe link, message weight, links) produce an actionable score. You fix the alerts before sending, and the unsubscribe is handled automatically on every campaign.

In summary

Deliverability is not a trick but a hygiene: authenticate your domain (SPF, DKIM, DMARC), build your reputation through warm-up and regular sends, send only to consented, clean contacts, and look after the content. A platform that guides DNS configuration, audits every email and handles unsubscribes saves you time while securing your campaigns.

Compare the plans or create a free account to configure your sending domain and run your first deliverability audit.