Blog Guides 6 min read
Best time to send cold email: what the evidence supports
By Wade, Duckrow's research duck. Updated .
The short answer
No mailbox provider, regulator or independent study publishes a best time to send cold email. The data that exists comes from vendors measuring their own customers: Belkins found replies peaked on weekday mornings across 7.5 million emails in 2025, and Instantly reports Wednesday as its best day. Treat both as hints, send in your recipients' working hours, and test.
Is there an official best time to send cold email?
No. Google, Yahoo and Microsoft publish rules on authentication, spam rates and unsubscribing, and none of them name a day or hour. What Google does say about timing is about pace: "Send email at a consistent rate. Avoid sending email in bursts." (Email sender guidelines, checked October 21, 2026.)
Google also says "Google doesn't track open rates" and that low open rates "aren't necessarily an accurate indicator of deliverability". Many timing studies are built on opens, so look for ones that count replies.
Texting is different: US rules bar telephone solicitations before 8 a.m. or after 9 p.m. at the recipient's location. That rule doesn't cover email.
What do the vendor studies report?
Two recent studies count replies, and both come from companies that sell outbound services or software. We report them as vendor findings:
| Study | Sample | Timing finding |
|---|---|---|
| Belkins (outbound agency), 2026 study, updated June 26, 2026 | 7,530,489 cold emails from its client campaigns in 2025; reply rate is replies divided by emails sent; opens not tracked | Morning (8 a.m. to noon) 0.54% against a 0.45% average; early morning (5 to 8 a.m.) 0.52%; late evening and night 0.40%. Wednesday and Thursday 0.48% each. Sunday 0.57% on only 21,615 emails, which Belkins calls statistically noisy |
| Instantly (cold email software), benchmark report, updated January 12, 2026 | "Billions of cold email interactions across thousands of active workspaces", January 1 to December 18, 2025; no exact count | "Tuesday-Wednesday see peak reply rates, Wednesday is highest"; Friday brings the most auto-replies. No reply rates by day are published |
Belkins' page doesn't say whether its hours are in the sender's or the recipient's time zone. Belkins also notes that in its earlier studies late evenings performed best, so its own finding changed from one year to the next.
How much does timing matter in that data?
Less than who you write to. In Belkins' data, the best time slot beat the average by 0.09 percentage points: about one extra reply per 1,100 emails. Belkins treats differences under 0.05 points as within its margin of error. In the same study, emails to companies with 0 to 10 employees got 0.72% against 0.22% at companies of 10,000 or more, a gap more than five times larger than the timing gap.
So pick sensible hours, then spend your effort on the list and the first line.
Whose time zone should you use?
Your recipient's. An email that arrives at 9 a.m. in Toronto lands at 6 a.m. in Vancouver. In Duckrow, each campaign has one schedule with one time zone, so for leads across North America either run a campaign per region or choose hours that fall inside the working day in every zone you reach.
What schedule should you start with?
Duckrow's default, which is our own choice and backed by no provider: Monday to Friday, 9 a.m. to 5 p.m. in the campaign's time zone. Then test against your own replies:
- Change one thing at a time, such as mornings only against the full day.
- Run two campaigns on similar lists at the same time, because Duckrow has no built-in A/B test.
- Count replies per email sent, and ignore auto-replies.
- Wait for a few hundred sends on each side before reading anything into a gap smaller than Belkins' own margin.
This post covers timing practice and is not legal advice. For texts, follow the quiet-hours rules in our guide to a first text.
Wade, Duckrow's research duck
Wade is the pen name of Duckrow's research desk. Every post is researched by the team, checked against its sources and dated, and updated when the facts change.
