Deliverability you can see, not just trust.

Every domain we set up gets the records Gmail, Yahoo and Microsoft look for. Every inbox gets a health score with a formula you can read. And the rules that protect your domains are on before your first send.

getnorthwind.com · zonechecked nightly
  • getnorthwind.com.MX1 smtp.google.com.Mail is handled by Google.
  • getnorthwind.com.TXT"v=spf1 include:_spf.google.com ~all"SPF says Google is allowed to send for this domain.
  • google._domainkeyTXT"v=DKIM1; k=rsa; p=MIIBIjANBgkqhkiG9w0BAQEF…"DKIM signs each email with a 2048-bit key, so it can't be changed on the way.
  • _dmarcTXT"v=DMARC1; p=none; fo=1; adkim=r; aspf=r"DMARC ties SPF and DKIM to the From address and asks for reports.
  • trackCNAMEtrack.emeraldsend.com.Opens and clicks, if you turn them on, use your own subdomain.
Example domain. Every domain bought here gets these records. Domains you bring are checked for the same ones, with the exact fix shown if one fails.

One number per inbox. No secret recipe.

Each night every inbox gets a score from 0 to 100. Most of it is where warmup emails landed. The rest is bounces and blocks.

score = round(
  0.60 × placement_7d
+ 0.25 × (100 − min(100, bounce_rate_7d × 20))
+ 0.15 × (100 − min(100, 50 × blocks_7d))
)
96%
1.0%
0

This is a calculator with numbers you choose, not data from a real inbox. Emails moved out of Promotions count as half a landing.

Health score
93
90–100

At 90 or above, an inbox with 14 days of warmup is ready for campaigns.

How the score adds up
0.6 × 9657.6
0.25 × (100 − 20)20.0
0.15 × (100 − 0)15.0

Warmup that acts like real people.

Inboxes in the network send each other plain, business-like emails during working hours. Each new inbox starts at 2 a day and adds 2 a day until it reaches 40.

An inbox never warms with inboxes from its own workspace or domain, and the same two inboxes are less likely to meet again within a week. A workspace whose inboxes land poorly stops receiving warmup from others, so one bad sender can't drag the network down.

The network is new, so we don't publish a size. What we do show is each inbox's own placement, every day.

  1. Delivered
    A warmup email arrives from another customer's inbox.
  2. Found in spam?
    It is moved to the inbox and counted as rescued.
  3. Found in Promotions?
    It is moved to the main inbox.
  4. Opened
    Every warmup email is opened.
  5. Marked important
    About 30% are starred or marked important.
  6. Replied
    About 30% get a reply in the same thread.
  7. Filed away
    Then it is archived under a warmup label, out of your way.

When something goes wrong, it stops first.

These checks run every 15 minutes for campaigns and every night for health. They are on by default.

Automatic pause and rest rules
WhenWhat happens
Campaign bounce rate > 5% over the last 100 sendsThe campaign pauses itself and tells you the rate it hit.
Inbox bounce rate > 5% over the last 50 sendsThat inbox rests from campaigns for 48 hours.
Spam complaints > 0.3% across the workspaceAll sending pauses and our team is alerted.
Health below 70 for 2 days in a rowThe inbox goes Resting: out of campaigns, still warming.
Health back at 85 or moreIt returns to campaigns on its own.
A policy block (SMTP 5.7.x)That inbox rests for 24 hours.

Low limits, on purpose.

Google lets a Workspace user send far more than this, roughly 2,000 emails a day. Cold email does best well under that, so our caps are much lower, and you can't raise them past the hard ceiling. Sends are spread out with random gaps, only during the hours you choose.

  • Campaign sends, default30/day
    per Google inbox per day
  • Campaign sends, most you can set50/day
    per Google inbox per day
  • Warmup, default target40/day
    reached over the first weeks
  • Warmup, most you can set100/day
    per inbox per day

Inboxes you connect have their own ceilings: up to 30 a day for Microsoft 365 and 100 for SMTP.

What Gmail, Yahoo and Microsoft ask for, and how we do it.

Mailbox provider sender requirements and how Emerald Send meets them
RuleWho asks, since whenHow Emerald Send meets it
SPF and DKIMGmail and Yahoo, Feb 2024. Microsoft Outlook.com, May 5, 2025.Written at setup with a 2048-bit DKIM key, then checked every night.
DMARC, aligned with the From addressGmail and Yahoo, Feb 2024. Microsoft Outlook.com, May 5, 2025.A DMARC record on every domain. Emails are sent and signed as the inbox's own domain, so they line up.
One-click unsubscribeGmail and Yahoo, Feb 2024.List-Unsubscribe and List-Unsubscribe-Post headers on every email, on by default. Locked on once you send over 5,000 a day to Gmail. An unsubscribe stops every campaign for that person at once.
Spam complaints under 0.3%Gmail and Yahoo, Feb 2024.Workspace sending pauses automatically above 0.3%.
Stricter enforcementGmail, Nov 2025: mail that breaks the rules is rejected, not just delayed. Microsoft sends it to junk.Every email carries those headers and a footer with your address and an unsubscribe link. A campaign can't launch until your address is set.

The bulk-sender rules apply to senders of about 5,000 or more emails a day to that provider. As of Oct 2026. Sources: Google sender guidelines, Yahoo sender best practices, Spam Resource, Nov 2025, Slashdot, May 2025.

No one can guarantee inbox placement.

Not us, and not anyone else. Gmail, Yahoo and Microsoft decide where each email goes, and they don't share how. What we can do is set everything up right, show you the numbers, and stop sending before a problem grows.

The rest is yours: who you write to, what you say, and how many you send. Clean lists, plain emails and a real reason to reach out do more than any setting. We verify emails before they are sent to help with the first part.

See your own records and scores in the trial.

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