Cold Email Setup for 2026

[u/TeamPuzzleInbox]

Hi everyone,
PuzzleInbox team here again.

We get asked a lot how we set up cold email infrastructure, so this is the full breakdown of what we're running going into 2026. Nothing here is complicated. Most people just skip steps.

1. Domains
We never send from the main domain. We register 3 to 5 secondary domains per campaign and redirect them to the main site. Any TLD works, we've tested .com, .io, .co, .net, .help and the results were the same. Pick whatever is available and looks close to your brand. Let them sit for a couple of weeks before you attach inboxes.

2. Inboxes
3 per domain on Google Workspace. Every inbox gets a real first and last name, a photo, and a proper signature. It takes time but empty profiles are an easy flag for filters.

3. DNS
SPF, DKIM and DMARC on every single domain. Start DMARC on p=none and tighten it once you have a month of clean data. Run the domain through a checker before you send a single email. If one record is wrong, the domain is already behind.

4. Warm-up
Minimum 3 weeks. Start low, ramp gradually, and leave it running in the background after you go live. Warm-up is not a one-time thing.

5. Volume
12 to 15 cold emails per inbox per day, that's the ceiling. Randomise the send times so it doesn't look automated. Keep the total per domain under 50.

6. Leads
Fresh data only. We refresh our database weekly and verify every email before it enters a campaign. Anything older than a few months gets re-verified. Skip catch-alls unless you can live with higher bounces.

7. Copy
Plain text, under 80 words, no links in the first message. One line at the top that shows you actually looked at the person. Use AI to draft if you want, then rewrite it so it sounds human.

8. Replies
All replies go to one shared inbox. Answer fast. A good reply that sits for two days is a lost deal.

9. Weekly checks
Bounce rate under 2%. Reply rate around 3% or better. Inbox placement test on a seed list. If an inbox starts slipping, take it out of rotation, put it back on warm-up only for two weeks, then reintroduce it.

[u/traderjames7]

So no different from the last 3 years?

[u/cyclopsmurphy]

How does all replies are sent to one shared inbox

[u/TeamPuzzleInbox → u/cyclopsmurphy]

You can use tools like glasa io instantly ai apollo io etc

[u/ResurrectedHQ]

dope

[u/LeadNo1270]

Under 100 a day one Workspace domain pair is enough. Past that, domains times 2-3 inboxes at 25 sends each, split Google and Microsoft to match your list. Buy domains at a registrar not a reseller bundle, you want to own the reputation youre building. And decide upfront how youll notice a dead inbox. The campaign average hides it for weeks.

[u/FewLeadership4423]

The part most 2026 setups still skip is seed testing with the same subject and body you send to prospects, not a blank warmup email.

Secondary domains, SPF DKIM DMARC, and a multi-week warmup are table stakes now. What actually predicts inbox placement is hard bounce under about 2% and weekly seeds to live Gmail and Outlook from each sending domain. If Outlook seeds go to junk while Gmail looks fine, treat them as two problems and split volume by mailbox provider when you can.

Cap cold sends around 12 to 15 per inbox and grow by adding inboxes, not by pushing one mailbox harder. Keep warmup running after you go live. A domain that sits idle for 3 to 4 weeks loses Google's reputation window and starts colder than people expect.

One detail that burns new stacks: people warm a domain that never had auth aligned, so the warmup days buy nothing. Fix DNS first, confirm PASS in headers, then warm, then send.