- Setup Register a sending domain and add SPF, DKIM and DMARC
- First weeks Named inboxes send a few personal emails a day
- Following weeks Raise volume gradually with people likely to reply
- First campaign Send only to verified addresses under a daily cap
- Every week Check bounces, complaints and replies, pause if worse
A great cold email is useless if it lands in spam. Mailbox providers judge each sender on authentication, history and how recipients react. Small teams often skip the setup, send a big batch from the company domain and then wonder why replies dry up and customer emails start going missing.
Why it works
Mailbox providers decide where each email lands based on the sender’s reputation. That reputation comes from authentication, sending history and how recipients react. Replies help, while bounces and spam reports hurt. A new domain has no history, so a sudden burst of email from it looks exactly like spam.
Moving outbound to its own domain limits the damage if something goes wrong. Your main domain keeps its reputation for the invoices, password resets and support emails customers rely on.
How to do it
- Register a separate sending domain. Pick one close to your brand, such as a variant of your name with a different ending or a short prefix. Point its website to your main site so it looks legitimate.
- Set up SPF, DKIM and DMARC. Your email provider will give you the DNS records. Start DMARC with a monitoring policy and tighten it once reports look clean. Check everything with a header test before sending.
- Create a few real inboxes. Use named people with a photo, a signature and a working reply path. Spread volume across inboxes instead of pushing one hard.
- Warm up slowly. Begin with a handful of emails a day to people likely to reply, and raise volume gradually over several weeks.
- Keep daily volume per inbox low. Set a modest cap and hold it even when you are in a hurry. Add inboxes to grow, never send more from each.
- Verify every list before sending. Run addresses through a verification service and drop invalid, risky and catch-all addresses where you can. Bounces are a strong spam signal.
- Write for replies and watch the numbers. Use plain text, few links, no attachments and an easy way to opt out. Track bounce rate, spam complaints and reply rate weekly, and pause a domain the moment they get worse.
Example
A two-person team selling compliance software to dental practices wants to start outbound. They buy a second domain based on their brand name, set it to redirect to their main site and create two inboxes for the founders. After adding SPF, DKIM and DMARC records, they spend the first weeks sending a few personal emails a day to existing contacts and partners. Their first real campaign goes only to verified addresses, with a small daily cap per inbox. When one inbox shows a rise in bounces, they pause it, clean the list and resume at a lower volume.
Metrics to track
- Bounce rate per inbox and campaign. Keep it low and steady, and investigate any jump.
- Spam complaint rate, from your provider’s postmaster tools where available.
- Reply rate, which reflects both deliverability and message quality.
- Inbox placement in seed tests across the major mailbox providers.
- DMARC report results, to confirm authentication keeps passing.
When it backfires
- Volume over quality. Adding domains and inboxes to send more poor emails only spreads the damage around.
- Lookalike domains that seem deceptive. A domain that imitates another company, or hides who you are, invites complaints and legal trouble.
- Ignoring the law. Rules on cold outreach differ by country. Check what applies to your recipients and always honour opt-outs.
- Set and forget. DNS records break, lists decay and providers change rules. Check your setup and metrics regularly.
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Questions people ask
Why not send cold email from our main domain?
If recipients mark your outreach as spam, the damage sticks to the domain that sent it. Using a separate but clearly related domain keeps invoices, password resets and customer emails on your main domain safe.
How long does warm-up take?
Plan on a few weeks of low, gradually rising volume with real conversations before running full campaigns. Rushing it is the most common way new domains end up in spam folders.
Should I use an automated warm-up service?
Some teams do, but real conversations with people who reply are the stronger signal. If you use a service, treat it as an addition to genuine sending and check that it fits your email provider's terms.