Dynamic Content in Emails: Implementation and Deliverability Impact

What Dynamic Content Actually Means

Dynamic content isn't just "Hi {first_name}." It's conditional email sections that change based on who's receiving the email. One template, multiple versions rendered at send time.

Simple example: An ecommerce email shows different product recommendations based on the recipient's last purchase category.

Complex example: A SaaS email changes the CTA, case study, pricing section, and footer based on the recipient's plan tier, industry, and engagement score.

Types of Dynamic Content

Merge Tags (Basic)

Replace placeholders with contact data:

• {first_name} → "Sarah"
• {company} → "Acme Corp"
• {last_purchase_date} → "March 15"

Available on every ESP. Low complexity, low risk.

Conditional Blocks (Intermediate)

Show or hide entire content sections based on conditions:

• If tag = "enterprise" → show enterprise pricing
• If location = "US" → show US-specific offer
• If last_purchase > 90 days → show winback offer

This is where dynamic content gets powerful. One email template serves multiple audience segments.

Computed Content (Advanced)

Content generated from calculations or external data:

• Product recommendations from ML models
• Countdown timers based on individual deadlines
• Pricing calculated from usage data
• Inventory status pulled at render time

Requires API integrations or advanced ESP features.

Implementation by ESP

ESP	Dynamic Syntax	Conditional Blocks	Product Feeds	Complexity
Klaviyo	Liquid/Django	Visual + code	Built-in AI recs	High
ActiveCampaign	Conditional content	Visual editor	Via integration	Medium
HubSpot	HubL	Smart content	Via API	Medium-High
Mailchimp	Merge tags	Content blocks	Product recs	Medium
SendGrid	Handlebars	Dynamic templates	Via API	High

Klaviyo Example

Klaviyo uses Django-style template syntax:

{% if person.tags contains "vip" %}
  Your exclusive VIP offer: 30% off everything
{% else %}
  Members save 15% this week
{% endif %}

HubSpot Example

HubSpot uses "Smart Content" modules that switch based on contact properties, list membership, or lifecycle stage. Configure in the visual editor without writing code.

Deliverability Impact

When Dynamic Content Helps

• Higher relevance = higher engagement. Showing relevant products, offers, and content increases click rates. ISPs see better engagement and reward your sender reputation.
• Reduced unsubscribes. Contacts receiving content matched to their interests are less likely to unsubscribe or complain.
• Cleaner sends. Instead of blasting the same generic email to everyone, dynamic content lets you maintain audience-specific messaging within fewer campaigns.

When Dynamic Content Hurts

• Complex HTML bloat. Every conditional block adds HTML to the email, even for blocks that aren't displayed. An email with 15 conditional sections can have massive HTML that triggers content filters or renders poorly.
• Too many links. Each dynamic product block or CTA adds tracked links. Emails with 20+ unique tracked links look suspicious to spam filters — see our guide on email link best practices.
• Rendering failures. If a dynamic block fails to render (missing data, template error), the recipient sees broken HTML or placeholder text. This looks spammy.
• Fallback content gaps. Dynamic blocks without fallback content show blank space when conditions aren't met.

Practitioner note: The biggest dynamic content failure I see is missing fallback content. A product recommendation block that shows "No products found" or an empty section because the data feed failed. Always define fallback content for every dynamic block — and test with contacts who have minimal data.

Best Practices

Keep It Simple

Start with 2-3 dynamic sections per email, not 15. Each dynamic block adds complexity and potential failure points. The most effective dynamic emails use:

• Personalized greeting (merge tag)
• One conditional content section (offer or product)
• One conditional CTA (based on lifecycle stage)

Always Define Fallbacks

Every conditional block needs an else clause:

• If no first name → use "there" or omit the greeting line entirely
• If no product recommendations → show bestsellers
• If no purchase history → show popular categories

Test Every Variation

Create test contacts that represent each combination of conditions. If you have 3 dynamic blocks with 2 states each, that's 8 possible email versions. Test all 8 across multiple email clients.

Monitor Per-Variation Engagement

Track engagement at the dynamic content level, not just the email level. If one variation has significantly lower engagement, the content isn't resonating — the dynamic logic might need adjustment.

Practitioner note: I've seen emails with dynamic content where the "enterprise" variation had 35% open rates and the "SMB" variation had 8%. Same email, wildly different performance. Without per-variation tracking, the blended 18% open rate looked acceptable. Track each version independently.

HTML Size Considerations

Dynamic content can balloon email HTML size. ISPs have soft limits:

Provider	Soft Limit	What Happens Over Limit
Gmail	~102 KB	Message clipped ("View entire message" link)
Outlook	~100 KB	Possible rendering issues
Yahoo	~100 KB	Similar clipping

If your dynamic template with all conditional blocks included exceeds 80 KB, trim it. Use fewer blocks, simpler HTML, or separate templates for significantly different audiences instead of one mega-template.

Practitioner note: Gmail's message clipping is the most common dynamic content problem. Your beautifully personalized email renders perfectly in testing, but the conditional HTML pushes it over 102 KB and Gmail clips the bottom half — cutting off your CTA. Check total HTML size with all blocks expanded.

For help implementing dynamic content strategies that improve engagement without creating deliverability risks, schedule a consultation.

Sources

• Klaviyo: Dynamic Content Documentation
• HubSpot: Smart Content Guide
• Litmus: Email Client Market Share
• Google: Gmail Message Size Limits
• ActiveCampaign: Conditional Content

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v1.0 · April 2026