# Should I send cold email from a separate domain, and how do I set one up?

Canonical: https://growfast.sh/solutions/set-up-a-separate-domain-for-cold-email | Last updated: 2026-11-13 | Published by GrowFast

For outreach, yes: keep it off the domain that carries your customer and transactional mail, so a bad run cannot damage that mail. Use a subdomain or a close variant of your domain, publish SPF, DKIM and DMARC, put a real identity on it and ramp slowly. GrowFast can send from a managed subdomain or from a domain you verify.

## Why it happens

Every sending domain and IP builds a reputation. Yahoo's guidance says to segregate email types by IP or DKIM domain and not to send bulk marketing from the same place as transactional mail, because each has its own reputation. Cold outreach is the category most likely to attract complaints, so it is the one to isolate.

The risk is not abstract. If your password resets and invoices share a domain with outreach that is flagged, they can end up in spam too.

## The fix that works without GrowFast

1. **Choose subdomain or look-alike.** A subdomain such as mail.yourcompany.com is simple, but we cannot promise receivers judge it separately from the parent. A look-alike domain isolates the main domain more strongly but needs to look legitimate and obviously yours.
2. **Register it and set up sending.** Use a mail provider or sender that supports your own domain, and add the DNS records it asks for.
3. **Authenticate it.** Publish SPF and DKIM, and DMARC with at least p=none. Check them with the lookups in the authentication guide.
4. **Give it a real identity.** Redirect the domain to your main site or put up a one-page site, send from a real person's name, and include your postal address and an unsubscribe link in the message.
5. **Do not mislead in the headers.** The FTC's CAN-SPAM guide requires accurate From, To and Reply-To information that identifies who sent the message. A look-alike domain must not pretend to be someone else.
6. **Ramp slowly.** Start at about 15 a day and raise gradually. A new domain has no reputation to lose and none to spend.
7. **Keep other mail separate.** Do not send newsletters or receipts from the outreach domain.

**Options compared (our assessment, 2026-11-13)**

| Option | Isolation from your main mail | Setup effort | Watch out for |
| --- | --- | --- | --- |
| Your main domain | None | None | Complaints land on the domain your customers receive mail from |
| A subdomain of it | Partial; receivers may relate it to the parent | Low | Not a guarantee of separate treatment |
| A look-alike domain | Strongest | Medium | Must be clearly yours; do not impersonate |
| A provider's managed address | From your domain: complete | None | Shared with the provider's other customers |

## When to use GrowFast

GrowFast offers two routes. The managed address is a mailbox on reach.growfast.sh, a subdomain GrowFast owns, so you need no DNS; replies come back through GrowFast and it ramps at 15 a day, then 30, then 50. Because that subdomain is shared by every GrowFast account, it is capped at 50 a day and accounts are paused when bounces or complaints rise.

Or connect your own domain: GrowFast shows the DNS records to add (DKIM and SPF), you verify, and the domain ramps up to 200 a day over four weeks. A verified domain whose sending address starts with mail. is capped at 50 a day, like the managed address; the 200 ceiling applies to other verified domains. Mailbox providers such as gmail.com cannot be used, because nobody can publish DKIM for them.

**When it is not the right tool:** If you want your own reputation and no shared subdomain, use your own domain. If you want to start in minutes with no DNS, the managed address is quicker but you share a reputation.

## Ask your AI assistant

Paste this into an assistant that has the GrowFast MCP server connected:

> Assign to GrowFast: list my sending domains and the managed address (list_sending_domains), say which are verified and how many sends each has left today. Don't send anything. Show me so I can approve which one to use.

Tools used: `list_sending_domains`. These need the full server (https://growfast.sh/api/mcp) with an API key.

## FAQ

### Is a look-alike domain deceptive?

Not if it is clearly yours, with a website pointing to your company, an honest From name and no impersonation. The FTC requires accurate header information.

### Can I send from my Gmail address?

GrowFast does not allow it: you cannot publish DKIM for a mailbox provider's domain. Use a domain you own.

### Does a new domain need warming?

It needs a gradual ramp. GrowFast enforces one on every sending domain.

### Which is safer, subdomain or look-alike?

A look-alike separates more strongly. A subdomain is easier. We cannot cite a receiver's statement on how it treats subdomains, so treat the difference as likely, not certain.

## Sources

- [Yahoo Sender Hub, Sender requirements and best practices](https://senders.yahooinc.com/best-practices) (read 2026-11-13)
- [FTC, CAN-SPAM Act: a compliance guide for business (page modified 2025-07-22)](https://www.ftc.gov/business-guidance/resources/can-spam-act-compliance-guide-business) (read 2026-11-13)
- [Google, Email sender guidelines (Gmail Help)](https://support.google.com/mail/answer/81126) (read 2026-11-13)

## Related

- [How many cold emails can I send per day without hurting my domain?](https://growfast.sh/solutions/how-many-cold-emails-per-day)
- [How do I check that SPF, DKIM and DMARC are set up before I send cold email?](https://growfast.sh/solutions/check-spf-dkim-dmarc-before-cold-email)
- [Why do my cold emails land in spam, and how do I fix it?](https://growfast.sh/solutions/why-do-cold-emails-go-to-spam)
- [All problems and solutions](https://growfast.sh/solutions)