Klaviyo Flows: Deliverability Considerations You're Probably Ignoring

The Deliverability Problem With Flows

Klaviyo flows are powerful. They're also automated cannons that will happily fire emails at unengaged contacts across multiple sequences simultaneously unless you tell them not to.

Here's what happens in a typical Shopify store with flows enabled:

• Welcome series fires 4 emails in 10 days
• Browse abandonment triggers for every product view
• Cart abandonment fires 3 emails per event
• Post-purchase fires another 3-4 emails
• Winback fires to anyone inactive for 60 days

A single contact can receive 15+ automated emails in a month from flows alone — before campaigns. If they're not engaged, that's 15 chances to generate a spam complaint.

Smart Sending: Don't Disable It

Klaviyo's smart sending sets a minimum gap between emails to the same profile. The default is 16 hours.

What it does: If a contact received any email (campaign or flow) within the smart sending window, the next flow email is skipped — not delayed, skipped.

Why people disable it: They want every flow email delivered regardless of timing. "But what about my abandoned cart sequence?!"

Why you shouldn't: Sending 3 emails in 24 hours to someone who hasn't opened any of them destroys your engagement metrics. Gmail sees low opens + high frequency and starts routing to spam.

The one exception: true transactional emails like order confirmations and shipping updates. But those should go through a transactional email provider anyway, not Klaviyo.

Practitioner note: I've audited Shopify stores that disabled smart sending and couldn't figure out why deliverability tanked. One store was sending 8-12 emails per week to contacts through overlapping flows. Turning smart sending back on and adding engagement filters brought their open rate from 12% back to 28% within three weeks.

Flow Filters: The Most Important Setting

Flow filters determine which profiles enter a flow. They're evaluated once, at the point of entry. This is different from conditional splits, which are evaluated at each step.

Critical Flow Filters to Add

For every non-welcome flow:

• "Has been active on email at least once in the last 120 days" (opened or clicked)
• "Has not been tagged as 'suppressed' or 'unengaged'"

For browse abandonment:

• "Has placed order zero times in the last 7 days" (don't send browse emails to recent buyers)
• "Has been in this flow zero times in the last 30 days" (prevent repeated triggering)

For cart abandonment:

• "Has started checkout at least once in the last 4 hours" (filter out bot carts)
• "Has not been in this flow in the last 7 days"

For winback:

• "Has been emailed at least 5 times" (only target contacts who had a chance to engage)
• "Has not opened email in the last 90 days" (actually inactive, not new)

Conditional Splits for Engagement

Inside flows, add conditional splits before key emails:

Split condition: "Has opened or clicked email at least once in the last 90 days"

• Yes path: Continue flow normally
• No path: Skip to end, or send one final re-engagement email with easy unsubscribe

This prevents your flows from repeatedly emailing contacts who have checked out mentally.

Flow Frequency Mapping

Map your active flows and calculate the maximum emails a contact could receive in a week:

Flow	Emails	Typical Timing
Welcome series	4-5	Days 1-14
Browse abandonment	2-3	Same day + 1 day
Cart abandonment	3	1hr, 24hr, 72hr
Post-purchase	3-4	Day 1, 3, 7, 14
Winback	2-3	Day 1, 7, 14
Cross-sell	2	Day 7, 14 post-purchase
Review request	1	Day 14 post-delivery

A contact who browses, abandons a cart, and then purchases could receive 8-10 emails in a single week. Smart sending helps, but it only skips — it doesn't guarantee reasonable frequency.

Solution: Use Klaviyo's "Has received email" condition to enforce maximum weekly sends. "Has received email at most 3 times in the last 7 days" as a flow filter prevents email fatigue.

Practitioner note: The stores with the best flow deliverability are the ones that treat flow frequency as a system, not individual flows. Map it out. Add up the maximum weekly emails. If a contact could theoretically receive more than 4-5 emails a week from flows, you need more aggressive filters.

Suppression From Flows

Klaviyo profiles that should be suppressed from flows:

• Hard bounces — Klaviyo handles this automatically
• Spam complaints — automatic suppression
• 120-day non-openers — manual suppression list or engagement filter
• Role-based emails (info@, admin@) — filter on import
• Unsubscribed — automatic, but check flow settings

Create a segment called "Flow Suppression" with profiles who haven't engaged in 120+ days and add it as an exclusion to every flow.

Transactional vs Marketing Flows

Klaviyo blurs the line between transactional and marketing email. Order confirmations sent through Klaviyo flows are technically marketing sends on shared infrastructure.

For critical transactional emails:

• Send through a dedicated transactional provider (Postmark, AWS SES)
• Use Klaviyo flows only for marketing-adjacent sequences
• Keep transactional sends separate from your marketing reputation

Practitioner note: I've seen order confirmation emails land in spam because the Klaviyo sending domain had degraded reputation from aggressive marketing flows. Separating transactional email onto its own subdomain and ESP is worth the setup time for any store doing 1,000+ orders per month.

Monitoring Flow Deliverability

Check these metrics weekly:

• Flow email open rates — should be 25%+ for engaged segments
• Flow spam complaint rate — must stay under 0.1%
• Flow unsubscribe rate — watch for spikes on specific emails
• Per-flow bounce rate — hard bounces should be near 0% (lists should be clean)

If any flow shows open rates below 15%, the flow is sending to too many unengaged profiles. Tighten filters.

For a complete audit of your Klaviyo flow structure and deliverability settings, book a deliverability consultation.

Sources

• Klaviyo: Smart Sending
• Klaviyo: Flow Filters
• Klaviyo: Deliverability Best Practices
• Google: Bulk Sender Guidelines
• Klaviyo: Engagement-Based Sending

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v1.0 · April 2026