Guide
Cold Email Domains: How Many You Need & What They Cost
Cold email domains are separate lookalike domains you send outreach from, so your main domain stays safe. Plan 3 inboxes per domain and about 30 emails per inbox per day.
Primary domain · never used for cold email
northwind.com
- getnorthwind.com3 mailboxes · SPF, DKIM, DMARC Ready
- trynorthwind.com3 mailboxes · SPF, DKIM, DMARC Ready
- northwindhq.com3 mailboxes · SPF, DKIM, DMARC Ready
Primary vs secondary
Primary domain vs cold email domain
Cold email domains carry the risk of outreach (spam complaints, bounces, blocklists) so your primary domain never has to. Each one is a secondary domain that looks like your brand and points visitors to your real site.
| Primary domain | Cold email domain | |
|---|---|---|
| Example | northwind.com | getnorthwind.com |
| Used for | Website, team email, invoices, support | Outbound prospecting only |
| If reputation drops | Customer and internal email suffers | Retire it and add a new one |
| Website | Your real site | Redirects to your real site |
| Authentication | SPF, DKIM, DMARC | SPF, DKIM, DMARC, set up per domain |
Sizing
How many domains and inboxes you need for cold email
Start from emails per day, not per month. These numbers use 30 cold emails per inbox per day and 3 inboxes per domain.
Step 1
Daily volume
How many new cold emails you send each weekday.
Step 2
÷ 30
Gives the number of inboxes, rounded up.
Step 3
÷ 3
Gives the number of domains, rounded up.
Step 4
Add spares
10–20% extra so you can rest any inbox that slips.
| Emails / day | Emails / month | Inboxes | Domains |
|---|---|---|---|
| 500 | 11,000 | 17 | 6 |
| 1,000 | 22,000 | 34 | 12 |
| 2,500 | 55,000 | 84 | 28 |
| 5,000 | 110,000 | 167 | 56 |
| 10,000 | 220,000 | 334 | 112 |
Cost
Cold email domain setup cost
Two things cost money: domains ($15 a year each on Jetmail) and the mailboxes on them. DNS setup is included.
Monthly cost of domains and mailboxes by daily volume
Jetmail standard mailboxes, cheapest plan for that count, billed monthly, plus domains at $15/year spread over 12 months.
| 500 / day | $71 |
|---|---|
| 1,000 / day | $127 |
| 2,500 / day | $310 |
| 5,000 / day | $570 |
| 10,000 / day | $1,141 |
| Emails / day | Domains | Domains / month | Mailboxes / month | Total / month |
|---|---|---|---|---|
| 500 | 6 | $8 | $64 | $71 |
| 1,000 | 12 | $15 | $112 | $127 |
| 2,500 | 28 | $35 | $275 | $310 |
| 5,000 | 56 | $70 | $500 | $570 |
| 10,000 | 112 | $140 | $1,001 | $1,141 |
Domains bought in Jetmail stay yours
Extensions
Best domain extension for cold email
Pick the extension your prospects will trust at a glance. In order of preference:
| Extension | How it reads to a prospect | Use it when |
|---|---|---|
| .com | The default for a business; most familiar | Always try first |
| .co | Close to .com, but can look like a typo | The .com variants you want are taken |
| .io / .ai | Normal in tech and SaaS, less so elsewhere | You sell to technical buyers |
| .net / .org | Established; .org suggests a nonprofit | .net as a fallback; .org only if you are one |
| Country code (.de, .co.uk) | Local and trustworthy in that market | You only email that country |
| Cheap new extensions | Unfamiliar to many recipients | Avoid for outreach |
Naming your secondary domains for cold email
- Keep the brand recognizable: get-, try-, use- or join- in front, or -hq and -team after.
- Avoid hyphens, numbers and misspellings that look like phishing.
- Redirect each domain's website to your main site so curious prospects land somewhere real.
- Some tools restrict extensions: Instantly's done-for-you setup only supports .com and .org.
Calculator
Plan your cold email domains
- Mailboxes
- 46
- Domains
- 16
- Jetmail / mo
- $151
30 sends per mailbox per day, 3 mailboxes per domain, 22 sending days. Monthly billing, mailboxes only (domains are extra with every provider). Competitor prices from their public sites, checked Oct 2026.
Monthly cost for 46 mailboxes
- Jetmail$151
- Zapmail$151
- InboxKit$138
- Icemail$115
- Instantly$230
- Zapmail prices shown are first-year prices; its help center says Google Workspace plans rise to $49/$149/$449 after 12 months.
- InboxKit pre-warmed shown at its cheapest tier (2–4 weeks warmed), excluding one-time domain transfer fees.
- Icemail standard price is a limited-time promo ($3.50 list).
- Instantly accounts also need a paid Instantly sending plan (from $47/mo), not included above.
Get this quote by email
We'll send the breakdown plus a domain and DNS plan for 30,000 emails a month.
Next: set up the mailboxes on those domains with cold email infrastructure, warm them up with the email warmup guide, and check each domain with the SPF checker.
Sources: Google email sender guidelines · Instantly: DFY domain rules
Get a free domain and inbox plan
Tell us where to send it. We'll reply with mailbox, domain and DNS recommendations for your sending volume — or start right away and have mailboxes live in minutes.
Where should we send it?
Or see pricing →Frequently asked questions
How many domains and inboxes do I need for cold email?
Divide your daily volume by 30 emails per inbox to get inboxes, then by 3 inboxes per domain to get domains. 1,000 cold emails a day takes 34 inboxes on 12 domains.
What does a cold email domain setup cost?
On Jetmail, a domain costs $15 a year and mailboxes are billed monthly. A setup for 1,000 emails a day (34 mailboxes, 12 domains) comes to about $127 a month, domains included.
What's the difference between a primary domain and a cold email domain?
Your primary domain is your company's main domain: your website, your team's email, your invoices. A cold email domain is a separate secondary domain that looks like your brand (for example getnorthwind.com) and is only used for outreach, so any reputation damage stays off the primary.
Should I use a secondary domain or a subdomain for cold email?
A separate secondary domain. A subdomain such as mail.northwind.com still sits under your main domain, so problems with it can reflect on the brand you're trying to protect.
What is the best domain extension for cold email?
.com. It's the extension recipients recognize most, and some tools only support .com and .org for done-for-you setups. Use .co, .io or a country code only when the .com variants you want are taken.
How many mailboxes should I put on one cold email domain?
We plan for 3. Fewer mailboxes per domain means more domains, but a problem on one domain affects fewer mailboxes. Some providers allow more; Instantly's done-for-you setup allows up to 5.