Portal active

Search Knowledge Base Articles

Find answers, guides, and documentation

Knowledge Base › Email Marketing Best Practices

Email Marketing Best Practices

This article is a comprehensive guide to email marketing best practices covering consent, content, technical configuration, list management, and deliverability. Following these guidelines consistently will maximise your inbox placement, open rates, and long-term sender reputation.

1. Consent & Compliance

Practice Why It Matters
Always use explicit opt-in Required by GDPR, CAN-SPAM, and most regional laws. Pre-ticked checkboxes do not constitute valid consent. Use a clear, affirmative opt-in.
Use double opt-in Sends a confirmation email that the subscriber must click before being added to your list. Produces a higher-quality, more engaged list and is almost mandatory for EU audiences under GDPR.
Never buy email lists Purchased lists contain invalid addresses (high bounce rate), spam traps (which flag you to ISPs), and people who never consented — a guaranteed way to destroy your sender reputation.
Include physical mailing address Required by CAN-SPAM (USA) and recommended globally. Include your registered business address in the email footer.
Include a clear unsubscribe link Every marketing email must include an easy, one-click unsubscribe mechanism. Honour all unsubscribe requests within 10 business days (CAN-SPAM requirement).
Document your consent Keep records of when and how each subscriber gave consent — the date, the sign-up source, and the form language used. This evidence is essential if a spam complaint is disputed.

2. Technical Configuration

Practice Why It Matters
Publish SPF, DKIM, and DMARC The three authentication standards are the minimum requirement for inbox placement with major email providers (Gmail, Outlook, Yahoo). Without them, your emails will consistently land in spam.
Use a dedicated sending subdomain Send from email.yourcompany.com or newsletter.yourcompany.com rather than your root domain. Isolates marketing reputation from your main domain.
Set up a custom tracking domain Using your own subdomain for open and click tracking (rather than a shared tracking domain) improves deliverability and trust. Some ISPs and spam filters flag generic tracking domains.
Use a consistent From address ISPs and recipients learn to trust your From address over time. Changing it frequently resets that trust and can trigger spam filters.
Aim for a healthy text-to-image ratio Emails that are pure images with no text are flagged by spam filters. Maintain at least 60% text content. Always include a plain-text version of every HTML email.

3. Subject Line Best Practices

  • Keep it under 60 characters — anything longer is truncated in most mobile inboxes.
  • Avoid spam trigger words — words like FREE, GUARANTEED, ACT NOW, URGENT, and excessive punctuation (!!!, $$$) are flagged by spam filters.
  • Personalise when possible — adding the recipient's first name to the subject line consistently improves open rates.
  • Be specific, not vague — "3 things to improve email deliverability" outperforms "Our latest newsletter."
  • Test before sending at scale — run an A/B test on new subject line approaches before committing to a full send.
  • Avoid ALL CAPS — it reads as shouting and is a spam signal.

4. Content Best Practices

Practice Guidance
One email, one goal Every email should have a single, clear purpose. Multiple CTAs compete for attention and reduce click rates on all of them.
Lead with value Put the most important information at the top. Most recipients skim — if the value is not obvious in the first two lines, they move on.
Mobile-first design Over 60% of emails are opened on mobile. Design for single-column layouts, large fonts (16px minimum), and large tap-target buttons (44px minimum height).
Alt text on all images Many email clients block images by default. Alt text ensures your message is still conveyed when images do not load.
Plain text version Always send a plain text alternative with every HTML email. It improves deliverability, supports accessibility, and ensures readability in all email clients.
Keep total email size under 100 KB Gmail clips emails larger than 102 KB, cutting off your content and hiding your unsubscribe link. Optimise images and use hosted image URLs instead of embedded base64.

5. List Management Best Practices

  • Remove hard bounces immediately after every campaign. Continuing to send to hard-bounce addresses signals to ISPs that you are not managing your list responsibly.
  • Run re-engagement campaigns quarterly and remove subscribers who do not re-engage. A smaller, engaged list achieves better inbox placement than a large, inactive one.
  • Never send to a list you have not emailed in over 6 months without a re-permission campaign first. Cold lists have high complaint rates.
  • Segment your list — send targeted, relevant content to subsets rather than the same message to everyone. Relevance reduces spam complaints and unsubscribes.

6. Deliverability Best Practices

Signal Positive Impact Negative Impact
Bounce rate Below 2% — shows clean, managed list Above 5% — ISPs flag your IP/domain as spam risk
Spam complaint rate Below 0.1% — shows recipients want your email Above 0.3% — Gmail / Yahoo may block or throttle delivery
Open rate Above 20% — signals genuine engagement Consistently below 10% — signals poor list quality or relevance
Sending consistency Regular, predictable volume builds IP trust Sudden large spikes after inactivity trigger spam filters
Authentication SPF + DKIM + DMARC all passing Any authentication failure increases spam likelihood significantly

Next Steps

Did you find this article useful?
Related Articles