A few simple mistakes can wreck your open rate, drive unsubscribes and ruin deliverability. Here are the 10 pitfalls to avoid for high-performing campaigns.

Important: a single mistake on this list can sink an entire campaign. Use it as your pre-send checklist.

1. A long or boring subject line

Aim for 30-50 characters and spark curiosity. Avoid ALL CAPS and excessive exclamation points.

2. No mobile optimisation

More than 60% of emails are read on mobile. Use a responsive template and check the mobile preview.

3. Too many images, not enough text

Keep at least a 60% text-to-image ratio to escape spam filters and improve accessibility.

4. No clear call-to-action (CTA)

Pick one primary CTA: visible, well placed, and big enough to tap with a thumb.

5. No list segmentation

Sending the same email to everyone kills engagement. Segment by interest, behaviour or lifecycle.

6. Wrong sending frequency

Too often: people unsubscribe. Too rarely: they forget you. Test and iterate.

7. Skipping GDPR compliance

Unsubscribe link, legal mention and prior consent are mandatory. Mailpro includes them automatically.

8. Not testing before sending

Always send a test to yourself and a colleague. Check Gmail, Outlook and mobile.

9. Ignoring stats

Opens, clicks and unsubscribes are your compass — they tell you what to improve next time.

10. Never cleaning your lists

Hard bounces and inactives damage your reputation. Clean every 3 months.

Read more: email deliverability and what is email marketing.

Skip the rookie mistakes. Open a free Mailpro account — the editor flags common errors automatically.

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