Email Marketing Checklist

Without a specific goal, you cannot measure success or optimize future sends. Every design and copy decision should trace back to one objective.

CTR is the most reliable engagement metric post-Apple Mail Privacy Protection. Open rates are inflated by privacy proxies and should not be your primary KPI.

Sending the same email to your entire list kills engagement. Segmented campaigns drive 30% more opens and 50% more clicks than blast sends.

Engagement in the first 60 minutes after send is a strong signal to ISPs. Sending when your audience is active maximizes that early engagement window.

Unrecognized sender names trigger spam complaints. An unmonitored reply-to address means you miss customer replies that drive engagement signals.

Sudden volume increases are the number one trigger for ISP throttling. Consistent sending patterns build and maintain sender reputation.

Double opt-in reduces spam complaints by 75% and is a strong positive signal to ISPs. It is required under GDPR for EU recipients.

Even one send to a known invalid address tells ISPs you do not maintain list hygiene. Most ESPs auto-suppress bounces, but verify before major campaigns.

ISPs weigh recipient engagement heavily. Sending to unengaged contacts drags down your aggregate engagement rate, hurting inbox placement for everyone.

Old or imported lists contain spam traps that immediately damage sender reputation. Verification services catch these before you send.

Mandatory for Gmail, Yahoo, and Microsoft bulk senders since 2024. Without it, recipients use the spam button instead, which damages your reputation far more.

Google and Yahoo enforce a 48-hour maximum. Delays generate spam complaints and can trigger automated throttling of your entire sending domain.

A preference center lets subscribers reduce frequency instead of fully unsubscribing. This preserves the relationship and keeps your list healthier.

CAN-SPAM requires a physical postal address in every commercial email. CASL requires express consent for Canadian recipients. Non-compliance carries fines up to $43,792 per email.

SPF tells receiving servers which IPs are authorized to send for your domain. Missing SPF means your emails fail authentication checks at every major ISP.

DKIM proves your email was not altered in transit. 2048-bit keys are the current standard — 1024-bit keys are deprecated and considered weak by modern ISPs.

DMARC protects your domain from spoofing and phishing. Gmail and Yahoo require a DMARC record. Progress from p=none to p=quarantine to p=reject over time.

Shared tracking domains inherit the reputation of every other sender on that domain. A custom tracking domain isolates your reputation and improves inbox placement.

Alignment between your From domain, DKIM domain, and Return-Path domain strengthens DMARC pass rates and prevents authentication failures.

ISPs have no reputation data for new senders. Gradual volume increases with high engagement build trust. Sending full volume immediately triggers spam filters.

Subject lines over 50 characters get truncated on mobile. Misleading subjects violate CAN-SPAM and spike spam complaint rates.

The pre-header is your second subject line. If left blank, email clients show the first line of HTML, which is often an unsubscribe link or navigation text.

Multiple CTAs dilute click-through. A single focused CTA increases conversions and gives ISPs a clear positive engagement signal.

Personalized emails generate 26% more opens and 41% more clicks. Always include fallbacks so merge tags never render as blank or broken.

Image-heavy emails are flagged by spam filters and render as blank rectangles when images are blocked. A healthy text ratio ensures readability in all conditions.

Over 60% of email opens happen on mobile. A non-responsive layout drives immediate deletes, which ISPs interpret as negative engagement.

EU accessibility law (effective June 2025) requires accessible digital communications. Alt text also helps deliverability since it adds text content that filters can evaluate.

Broken links generate spam complaints from frustrated recipients. Typos in sender content erode trust and reduce future engagement rates.

Each email client renders HTML differently. What looks perfect in your ESP preview may be broken in the recipient's inbox.

Over 80% of mobile users use dark mode. Backgrounds, images with transparency, and text colors that work in light mode often fail in dark mode.

Pre-send spam scoring catches content and technical issues before they affect your real reputation. A score above 5/10 on Mail-Tester suggests problems.

A single broken merge tag displays raw code to the recipient, triggering spam complaints and destroying trust in your brand.

UTM-tagged links can break when URL encoding goes wrong. Verify that every link resolves to the correct page and analytics parameters are captured.

Statistical significance requires adequate sample size. A/B testing subject lines consistently improves CTR by 10-20% over time when done with proper holdout.

A hard bounce rate above 2% triggers immediate reputation damage. Catching it early lets you pause and investigate before the full list is processed.

Google, Yahoo, and Microsoft all enforce the 0.3% spam complaint threshold. Exceeding it triggers throttling or blocking that can take weeks to recover from.

Apple Mail Privacy Protection pre-fetches images, inflating open rates by 30-50%. Click-through rate is the only reliable measure of actual recipient engagement.

An email can pass all authentication checks and still land in spam due to content or reputation issues. Inbox placement testing confirms actual delivery.

Delayed unsubscribe processing results in sending to people who opted out, which generates spam complaints and can violate CAN-SPAM regulations.

Without systematic documentation, teams repeat mistakes. Record CTR, conversion rate, revenue, complaints, and bounces for every campaign.