Guide · Deliverability
Cold email domains and warm-up, set up properly.
By Nouman, founder · 17 October 2026
Set up cold email on separate secondary domains, never your main one, named so buyers recognise your brand. Authenticate each with SPF, DKIM and DMARC, give each a few real inboxes, and warm them up gradually before any campaign. A domain is ready when authentication passes, test messages land in the inbox and real people reply. Then send at a volume you've written down in advance, and rest any domain that starts landing in spam.
Seven steps
01 Use secondary domains, never your main one
Cold email carries more risk of spam complaints than ordinary mail. Sending it from a separate domain keeps any damage away from the domain your customers, invoices and password resets depend on.
02 Name them so a buyer recognises you
Close variations of your brand that a reader would connect to you, such as your name with a short prefix or suffix, or a different ending. Avoid anything that looks like a typo of someone else's brand, and point each one's website at your real site so a curious recipient lands somewhere sensible.
03 Authenticate every domain before sending anything
SPF, DKIM and DMARC on each domain, with the From domain aligned to what is signed. Check the result by sending yourself a message and reading "Show original" in Gmail.
04 Give each domain a few real inboxes
Named after real people on your team, with a photo, a signature and a working reply path. Spread sending across several inboxes rather than pushing one hard.
05 Warm up gradually
Start each new inbox with a small amount of mail to people likely to open and reply, and raise volume slowly over weeks. Hold or cut back the moment replies drop or test messages start landing in spam.
06 Know when a domain is ready
Authentication passes, your own test messages land in the inbox on Gmail and Outlook, bounces are near zero, and real recipients reply. Only then move it onto a real campaign, at a volume you have written down in advance.
07 Watch, rest and retire
Check placement every week. A domain that starts landing in spam gets rested, and if it doesn't recover, retired. That is the whole point of using secondary domains.
The provider rules behind step 3
Gmail requires every sender to set up SPF or DKIM, and senders of more than 5,000 messages a day to also set up DMARC, with the sending domain aligned (Google). Outlook has applied the same SPF, DKIM and DMARC requirements to domains sending more than 5,000 messages a day since 5 May 2025 (Microsoft). Cold email rarely reaches those volumes per domain, but set all three up anyway: they cost nothing to add and filters trust authenticated mail more.
Checked 17 October 2026.
Mistakes that burn domains
- Sending a campaign on day one. A new domain with no history and sudden volume looks like spam because it usually is.
- One inbox doing all the work. Spread it out.
- Tracking pixels and redirected links on a young domain. We don't use them in our own outreach.
- Unverified lists. Bounces do more damage to a new domain than to an established one.
- Nobody watching placement. By the time replies stop, the domain may already be burnt.
Or email Nouman: scipioform@gmail.com, or call +44 7400 754177 or WhatsApp