The State of Cold Email Deliverability Q3 2026
43 million cold emails from the last 60 days, boiled down to what to change.
43.0M
cold emails sent
447k
replies
129,608
sending domains
865k
inboxes
Data: last 60 days, Aug 6 – Oct 4, 2026. Per-domain rates use the latest 30 days.
The 9 things to fix first
From the last 60 days of sending. Tap one to see the data.
The best deliverability fix is an offer people actually want. Infrastructure keeps you out of spam; your offer gets the reply. These numbers also move week to week and depend on your list, copy and practices, so treat them as benchmarks, not guarantees.
How many emails should each inbox send?
Send under 5 a day per inbox on Azure, under 15 on Google
Emails per inbox per day vs how many of those domains are burned right now.
55%
of Azure domains sending 5–7/day are burned (11% under 5)
44%
of Google domains sending 15–19/day are burned (19% under 10)
−44%
Google reply rate at 15–19/day vs under 10
Azure: under 5 per inbox per day. Google: under ~15. Need more volume? Add inboxes instead of pushing harder.
Show the full data · charts by volume bucket
Microsoft Azure: share of domains burned
Emails per inbox per day
Google Workspace: share of domains burned
Emails per inbox per day
Google Workspace: reply rate per send
Emails per inbox per day
4,131 actively sending Azure domains and 21,133 Google domains. Volume = 30-day sends ÷ inboxes on the domain ÷ sending days. Most teams run Google at 15–25 and Azure at about 5, right where burn takes off.
Free · about 2 minutes
Get this report for your own domains
Connect Smartlead, Instantly, EmailBison or PlusVibe. Peeker shows every one of your domains' reply rate, bounce rate and health (healthy, underperforming or burned), updated daily, so you can hold each one against these benchmarks. Free, whoever supplies your inboxes.
vs Google median 0.97%
352
teams on Peeker
129,608
domains monitored
5,292
burned domains swapped in 60 days
Which inboxes should I use?
Google inboxes get more replies than Azure
Median reply rate per domain, last 30 days.
Median reply rate per domain
Default to Google Workspace. Azure is a solid second at low volume. Test SMTP small before you scale it.
Show the full data · same-team comparisons
1.29×
Google vs Azure reply rate, same 48 teams (Google won 32)
1.59×
Google vs SMTP, same 10 teams (Google won 9)
34%
of SMTP domains got zero replies in 30 days
Medians from 21,133 Google, 4,200 Azure and 3,814 SMTP domains with 200+ sends. Same-team comparisons only include teams with 5,000+ sends on both providers. Zero bounces on SMTP doesn't mean the mail reached the inbox.
Switching providers? Book a free deliverability session and move your Google and Azure inboxes at a guaranteed lower cost.
How long do domains last?
Most domains start to go bad after 2 to 4 months
Share of sending domains that are burned, by domain age.
40%
of Google domains aged 2–3 months are burned
47%
of Azure domains aged 4–6 months are burned
5,365
domains replaced by Peeker customers in 60 days
Have replacements warming by month 2 on Google and month 4 on Azure. Replacement is a routine, not an emergency.
Show the full data · burn by domain age
Google Workspace: % burned by age
Months since warm-up started
Microsoft Azure: % burned by age
Months since warm-up started
Age = days since warm-up started. A snapshot of today's domains, not a lifetime curve: burn looks lower after month 3 partly because burned domains get removed.
How do I know a domain is burned?
A burned domain stops getting replies, but still looks fine
Domains grouped by current health, last 30 days.
Reply rate per send
Burned domains reply 4.6× less with the same bounce rate. If you only watch bounces, you'll never see it coming. 7,325 burned domains were still sending last week.
Show the full data · bounces, zero-reply weeks + checklist
Bounce rate (median), last 30 days
Zero replies in the last 7 days
Reply rate per send, per domain, against its own 30-day average. A falling 7-day rate with flat bounces means it's probably landing in spam.
Zero replies in a week of real volume deserves a look. 62% of burned domains show it vs 17% of healthy ones.
Compare domains on the same campaign. If one trails its siblings on the same list and copy, the domain is the problem.
Domains with 50+ sends in the last 7 days: 10,825 healthy, 3,861 underperforming, 7,325 burned.
Find out which domains are landing in spam before your reply rate hits zero. Peeker checks every domain in your sequencer, free.
Check my domains freeDo Peeker domains do better?
Peeker domains get more replies and burn less
Domains bought through Peeker vs domains bought elsewhere, last 30 days.
1.67%
Peeker reply rate vs 0.92% on external domains
5.6%
of Peeker domains burned vs 25.2% external
5 min
median time to swap a burned domain automatically
Show the full data · by provider + method
Reply rate per send, by provider
Share of domains currently burned
Peeker swaps burned and underperforming domains automatically (5,292 swaps in 60 days). Peeker domains are also younger on average, which flatters the comparison; within the same teams, Peeker domains out-replied external ones in 7 of 11 cases (median 1.13×).
Switch your inboxes, keep your sending. We'll review your domains and move your current Google and Microsoft Azure inboxes to Peeker at a guaranteed lower cost.
What days should I send?
Weekdays work a little better than weekends
Reply rate per email sent by weekday, last 60 days.
Reply rate per send, by weekday
Show the full data · notes
Weekends: −10%. Saturday and Sunday reply at 0.95–0.96% vs 1.06% Tuesday to Thursday, and burn the same domain life.
Monday is the weakest weekday at 0.99%.
Thursday and Friday carry the most volume: 16.7M of the 43.0M sends, and they reply as well as midweek. Weekends carry only 10% of volume.
Which domain ending should I buy?
.com domains get the most replies
Each sender's .co and .info domains vs their own .com domains, last 30 days.
Reply rate vs the same sender's .com
Buy .com first. .co is close (−7%). Skip .info, even though it's 1 in 5 connected domains.
Show the full data · market share, raw-data trap, other TLDs
65%
of 129,608 connected domains are .com
20%
are .info (1 in 5)
10%
are .co
| Ending | vs .com | Senders | Verdict |
|---|---|---|---|
| .org | 1.15× | 10 | Fine, small sample |
| .net | 1.25× | 9 | Fine, small sample |
| .us | 0.70× | 3 | Too little data |
The raw-data trap: across all senders, .info replies at 1.19% vs 0.92% for .com. Compare the same senders and .info loses in 18 of 29 cases.
Does my email tool matter?
Your email tool matters less than how you use it
Google Workspace domains by email tool, last 30 days.
Reply rate per send on Google domains
EmailBison users post the best Google reply rate and the lowest burn; PlusVibe the highest Google burn (28%). That mostly reflects who uses each tool and how hard they send.
Show the full data · burn by tool
Share of Google domains burned, by tool
PlusVibe counts replies against contacted leads, so its reply rate isn't shown.
How many domains are healthy?
2 out of 5 sending domains have a problem
Health of every actively sending domain as of October 4, 2026.
54%
Healthy
4%
Improving
19%
Underperforming
23%
Burned
Only 54% of actively sending domains are healthy. And 56% of all inventory is warming, idle or disconnected: paid for, not sending.
“We test ran a new campaign with Peeker inboxes and got a 4% increase in reply rate compared to our manual inboxes.”
“Reply rates and inbox burn was an issue with previous inbox providers… the communication, setup time, and inbox swaps response time is great.”
“With Peeker, the pricing is amazing, the inboxes are reliable, and the support is great.”
Free · about 2 minutes
Get this report for your own domains
Connect Smartlead, Instantly, EmailBison or PlusVibe. Peeker shows every one of your domains' reply rate, bounce rate and health (healthy, underperforming or burned), updated daily, so you can hold each one against these benchmarks. Free, whoever supplies your inboxes.
vs Google median 0.97%
Then switch when you're ready: Peeker inboxes have the best prices on the market, swap burned and underperforming domains automatically (median 5 minutes), and include this whole deliverability suite free. See pricing
How we built this
- Window: the last 60 days, Aug 6 – Oct 4, 2026. Totals, weekly trends and weekday figures use daily sent, reply and bounce counts from 7,572 connected sequencer workspaces. Per-domain figures use each domain's latest 30 days (Sep 5 – Oct 4).
- 129,608 sending domains and 864,844 inboxes connected to Peeker via EmailBison, Smartlead, Instantly and PlusVibe. Reply-rate distributions use the 29,154 domains with 200+ sends in the 30-day window.
- Reply rate = replies ÷ emails sent. Bounce rate = bounces ÷ emails sent. Health statuses come from Peeker's daily domain health model.
- Emails per inbox per day = 30-day sends ÷ inboxes on the domain ÷ sending days. Domain age = days since warm-up started; age figures are a snapshot of today's domains.
- Same-team comparisons (Google vs Azure, domain endings, Peeker vs other) compare a team's domains with that team's own other domains, to control for list, copy and offer.
- These numbers change. They depend on each sender's lists, offers and practices, and will look different next quarter. Numbers are rounded.
