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Open rates dropping from 28% to 16%, campaigns landing in promotions, sudden bounces? Deliverability is the silent killer of email revenue. This is the systematic diagnostic specialists run before suggesting any fix.
Who this is forKlaviyo accounts where open rate has dropped 5+ points over the last 30 days, or where a recent campaign landed in spam/promotions widely. If you're getting 'your IP is on a blocklist' alerts, this is urgent.
What you'll need
Step 1
Klaviyo → Analytics → Deliverability → check sender reputation, bounce rate, complaint rate, and engagement trends.
Klaviyo → Analytics → Deliverability.
Look at 5 numbers: Bounce rate (<2% target), Spam complaint rate (<0.1% target), Open rate (>20% target), Click rate (>1% target), Unsubscribe rate (<0.5% target).
If bounce rate is >2% or complaint rate is >0.1%, deliverability is degrading and Gmail/Outlook are starting to filter you.
Compare to a 90-day baseline. A sudden drop in open rate (5+ points in 30 days) is the most reliable signal that something changed.
Note: Apple Mail Privacy Protection (MPP) inflates open rates by 30-50% on iOS. Adjust expectations — a "20%" open rate on Apple Mail-heavy lists is more like 13-15% real opens.
Step 2
Klaviyo → Account → Settings → Domains. All three should show "Authenticated" / "Valid" / "Pass."
Klaviyo → Account → Settings → Domains. Look at your sending domain.
Check: dedicated sending domain (e.g., send.yourbrand.com) is set up — NOT sending from yourbrand.com directly.
DKIM: should show "Valid" with the Klaviyo selector record present in DNS.
SPF: include:klaviyo-mail.com (or whatever Klaviyo specifies) should be in your SPF TXT record.
DMARC: At minimum p=none. p=quarantine or p=reject is better but only after you confirm DKIM + SPF are 100%.
Use mxtoolbox.com or dnschecker.org to verify the records publicly resolve. Sometimes DNS shows "saved" in your registrar but propagation has issues.
Step 3
New Klaviyo accounts or recently-changed sending domains start on a 'warmup' IP. Spikes in send volume can break the warmup curve.
Klaviyo → Analytics → Deliverability → check the "Sending volume" tab.
For a healthy warmup: volume scales from 500 emails/day → 5K/day → 50K/day over 4-6 weeks, with engagement (open rate) staying above 18%.
If you suddenly tried to send 50K emails on Day 3 of a new domain, Gmail/Outlook flagged you as a spam-volume sender. Recovery takes 30-60 days.
Fix: slow back down. Send to your top-engaged 10% segment only for 7 days, then top-30% for 7 days, then expand gradually. Don't try to "force through" — it makes the reputation worse.
Step 4
Sending to disengaged subscribers tanks reputation. Suppress profiles with no opens in 180 days before continuing.
Klaviyo → Lists & Segments → + Create Segment.
Segment definition: 'Subscribed to list X' AND 'Has not opened email in last 180 days' AND 'Has not clicked email in last 180 days' AND 'Has placed order in last 365 days' is false.
This identifies disengaged profiles eating your reputation.
Option A: suppress this segment from all sends (set them to "Excluded" on every campaign).
Option B: run a 1-2 email re-engagement flow ('Still interested? Click to stay subscribed'). Anyone who clicks stays; anyone who doesn't gets suppressed.
Plan to suppress 20-40% of your list this way. It hurts to do once, but lifts open rate 5-10 points across the rest of your sends.
Step 5
Use mxtoolbox.com/blacklists to check if your sending domain or IP is on a blocklist. If yes, request removal.
Visit mxtoolbox.com/blacklists. Enter your sending domain.
Check Klaviyo's dedicated IP (if you have one) at the same URL.
Common blocklists: Spamhaus, SURBL, Barracuda, SpamCop. Each has a removal-request form — search '[blocklist name] removal request.'
Most blocklists auto-remove after 30 days if you stop sending bad volume. Some require manual review (Spamhaus SBL).
Important: do NOT keep sending while you're blocklisted. Pause campaigns and only send transactional until removed.
Step 6
Pull a 90-day campaign-by-campaign report. Find the inflection point where engagement dropped.
Klaviyo → Campaigns → All campaigns → 90-day view.
Sort by send date. Look at Open Rate column.
Find the campaign(s) where open rate dropped 5+ points. What was different? Common culprits: a list purchase, a sudden 5x volume increase, a subject line that triggered spam filters, a sending-domain change.
Common bad-actor patterns: 'BUY NOW!!!' subject lines, all-caps, excessive exclamation, attachment-style file extensions in copy ('.exe', '.zip'), too many images and not enough text.
Once identified, the fix is to stop doing whatever caused it. If it was a list purchase, suppress the purchased list immediately.
Step 7
Send only to top-engaged 25-30% for 30 days. Watch open rate climb. Then expand gradually back.
Create a segment: 'Has opened or clicked email in last 30 days' AND active.
Send only to this segment for 30 days. Pause everything else.
After 30 days, expand to 'opened or clicked in last 60 days.'
After another 30 days, expand to 90 days. Continue.
Open rate should climb 8-15 points across the recovery. If it doesn't, the issue is structural (auth, blocklist) — not engagement.
Re-introducing disengaged profiles too fast restarts the cycle. This recovery is slow on purpose.
Common mistakes
Sending to your entire list to "wake them up"
What goes wrong: Sends to disengaged subscribers spike bounce + complaint rate. Mailbox providers see this and downrank you globally. Open rate drops from 28% to 16% and you don't recover for 60-90 days.
How to avoid: Suppress 180-day non-openers before any "wake-up" campaign. Use the engagement-based segment from Step 4 as your only audience until reputation recovers.
Sending from the root domain instead of a subdomain
What goes wrong: A reputation hit on root domain affects ALL your email — including transactional (order confirmations). One bad campaign can break your support inbox.
How to avoid: Move marketing sending to a subdomain (send.yourbrand.com or news.yourbrand.com). Keep transactional on the root domain. Klaviyo → Account → Settings → Domains.
No DMARC, or DMARC set to p=reject too early
What goes wrong: No DMARC: Gmail/Outlook are increasingly filtering. Premature p=reject: legitimate emails get blocked if any SPF/DKIM record has an issue.
How to avoid: Start with DMARC p=none and a rua= reporting address (use dmarcian.com free tier). Verify reports for 30 days. Then progress to p=quarantine, then p=reject.
Ignoring a sudden bounce-rate spike
What goes wrong: Bounce rate over 2% triggers ISP downranking. Continuing to send while bounce rate is high cements the reputation damage. Takes 90+ days to recover.
How to avoid: Klaviyo auto-suppresses hard bounces. If soft bounces are spiking, pause sending immediately. Diagnose: is there a list segment with stale emails? Did you import a CSV with bad data? Don't send again until bounce rate is back under 1%.
Buying a list and importing it
What goes wrong: Bought lists have 30-60% invalid emails and 95%+ disengagement. Sending to them spikes complaint rate, triggers blocklists, and can permanently damage your domain. Recovery from a single bought-list send can take 6 months.
How to avoid: Don't buy lists. Ever. If you already did and have sent — suppress everyone you imported in the last 90 days, send only to organically opted-in subscribers, and start the 30-day recovery from Step 7.
Image-only emails with no text
What goes wrong: Spam filters score image-only emails high-spam. Lands in promotions/spam regardless of sender reputation. Open rates plummet.
How to avoid: Maintain a 60/40 text-to-image ratio minimum. Every email should have at least 300 words of real text. Alt text on images.
Recap
Done — what's next
How to build Klaviyo segments for repeat buyers (RFM, predictive CLV, win-back)
Read the next tutorial
Hand it off
Deliverability problems compound — every day of sending while damaged makes recovery harder. A specialist diagnosis + recovery plan is typically $400-800 of one-time work at $14-16/hr. Ongoing deliverability monitoring is usually $200-400/mo. The alternative is 60-90 days of half-revenue while you DIY-debug.
See specialist rates
30-90 days for most cases. Mild issues (one bad campaign) recover in 30 days with proper hygiene. Severe issues (bought lists, blocklist entries) take 60-90 days. Catastrophic issues (sustained complaint rate >0.5%) may require migrating to a new sending domain entirely — 6+ months to fully rebuild.
Only if you send 250K+ emails/month consistently. Below that, dedicated IPs hurt deliverability — there's not enough volume to maintain reputation. Shared IPs (Klaviyo's default) work better for smaller volumes because Klaviyo's pool reputation is strong.
Under 2% total bounce rate. Hard bounces (invalid email) should be under 0.5% — Klaviyo auto-suppresses these. Soft bounces (full inbox, temporary issue) should be under 1.5%. Above these levels, mailbox providers start downranking you.
Gmail Promotions isn't the same as spam. Many marketing emails land there by design and still get opened. If open rate is acceptable (15%+ on a Gmail-heavy list), Promotions is fine. If open rate is dropping, the cause is usually content (too promotional, image-heavy, too many links) or reputation, not the Promotions tab itself.
Yes — but only to the top-engaged 25-30%. After 30 days of clean sending to this group, expand to 60-day engaged. After another 30 days, expand to 90-day engaged. Full list access returns at ~60-90 days. Trying to skip the gradual reopen restarts the damage cycle.
Klaviyo shows you the symptoms (open rate, bounce rate, complaint rate) but doesn't have a single 'reputation score' the way some tools do. Use Google Postmaster Tools (postmaster.google.com) to see your Gmail reputation directly — that's the ground truth for the 60%+ of recipients on Gmail.
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