In this chapter
- The 6 signs, and what each one cannot tell you
- 1. The health score: stable beats high
- 2. The inbox rate: read it by provider
- 3. The spam rescue trend: the quiet one
- 4. A placement test at your prospects' provider
- 5. Google Postmaster Tools, once you send volume
- 6. Your first small cold send
- 4 false alarms that do not mean warmup is broken
- What to do when the numbers are not improving
- Questions
Email warmup is working when four things move together: the health score climbs, most warmup email lands in the inbox, fewer warmup messages need rescuing from spam, and a test message to your prospects' provider lands in the primary inbox. In Warmerly's dashboard a mailbox reads as healthy at an average health score of 80 or more with 90% or more of warmup email in the inbox. Those numbers describe warmup traffic, so confirm them with a placement test and your first small cold send before you scale up.
Most warmup tools show a score and a chart, and most people read a green number as permission to send. That is half right. A good warmup score proves the mailbox behaves well inside the warmup network. It does not prove that Gmail or Outlook will treat your cold campaign the same way. Read the signals below in order, from the one you can trust least on its own to the one that is closest to a real send.
The 6 signs, and what each one cannot tell you
| Signal | Where to see it | A good reading | What it does not tell you |
|---|---|---|---|
| Health score | Your warmup dashboard, per mailbox | Average at or above 80 and holding, not spiking | How a cold campaign to strangers will land |
| Inbox rate of warmup email | Warmup stats for a date range | 90% or more in the inbox | Placement for mail that is not warmup traffic |
| Spam rescue trend | Your warmup tool, if it reports spam rescues | Fewer rescues each week | Anything about providers outside the warmup pool |
| Placement test | A test send to your prospects' provider | Primary inbox, not promotions or spam | More than one moment in time; one message is a small sample |
| Spam rate in Google Postmaster Tools | Google Postmaster Tools, for Gmail recipients | Reported spam rate below 0.1%, never reaching 0.3% | Anything until you send enough volume for Google to report |
| First cold sends | Bounce and reply rates on a small first batch | Few bounces, replies arriving, nothing in spam when you test | A clean list can hide a weak mailbox, and a dirty list can hide a good one |
1. The health score: stable beats high
The health score is a single number out of 100 for each mailbox. The useful question is not whether it touched 80 once but whether it has stayed there for several days. A score that jumps up and drops back is a mailbox still under review by the providers. Warmerly's dashboard words it simply: at an average of 80 or more with a 90% inbox rate it says your warmup is healthy, below that it says warmup is building, and below 50 or with a paused mailbox it says something needs attention.
2. The inbox rate: read it by provider
An overall inbox rate hides the split that matters. If most of your prospects use Gmail, a strong overall figure carried by Outlook recipients is not a pass. Look at the provider your list is made of. Early in warmup a lower rate is normal; what you want is a line that rises and then flattens near the top.
3. The spam rescue trend: the quiet one
Early in warmup some warmup messages land in spam. Warmerly finds them there, moves them to the inbox, marks them as not spam and answers them, because a message left in spam teaches the filter that the sender is junk. So how often a mailbox needs rescuing is a measure of how much the providers still distrust it. If your tool reports it, a falling count is one of the clearest signs that warmup is working, and a count that stays flat after two or three weeks is worth a look at authentication and volume.
Rescue applies only to warmup mail between Warmerly mailboxes. Your campaign mail to real prospects is never touched, which is exactly why the next three signs matter.
4. A placement test at your prospects' provider
A placement test sends a real message from the mailbox and then looks in the inbox, promotions and spam folders of a few target mailboxes. Run one at the provider most of your list uses. Treat it as a spot check: one test is one moment, and a test that falls back to warmup mailboxes as targets is less independent than one sent to mailboxes you do not control. If it lands in the primary inbox, that is encouraging. If it lands in promotions or spam, give warmup more time and check the authentication records before you send anything cold.
5. Google Postmaster Tools, once you send volume
Google publishes the line for bulk senders: keep the user-reported spam rate below 0.1% and never let it reach 0.3%. Postmaster Tools only shows data once enough mail reaches Gmail users, so it is silent during warmup and becomes useful in the first weeks of campaigns. Add your sending domain before you start so the history exists.
6. Your first small cold send
The last check is the real one. Send a small first batch to a clean, verified list and watch bounces, replies and where a test copy lands. Keep warmup running alongside campaigns, as the best practices chapter explains, so a new volume level does not undo what you built.
4 false alarms that do not mean warmup is broken
- A low score in the first days. A new mailbox has no history, so a low starting score is expected. Judge the direction over a week or two, not the first reading.
- One warmup message in spam. Single messages land in spam in healthy mailboxes too. Look at the rate over a date range, not at one message.
- A dip after you raise volume. More sending changes the pattern the providers see. Hold the volume for a few days before you change anything else.
- A good score on a mailbox you have not sent from. The score reflects warmup traffic only. It is not a promise about a campaign.
What to do when the numbers are not improving
- Check that no mailbox is paused or showing a connection error. A paused mailbox is not warming up, whatever the chart says.
- Confirm SPF, DKIM and DMARC pass for the sending domain. Warmup cannot fix broken authentication.
- Hold the daily volume where it is. Raising it while the score is low is the usual way to lose ground.
- Give a new domain more time than an aged one. The how long chapter has the ranges by domain age.
- If a domain has a history of spam complaints, consider a fresh domain rather than months of repair.
Questions
How do I know if my email warmup is working?
Four signs together: the health score rises and holds, most warmup email lands in the inbox, fewer warmup messages need rescuing from spam, and a test message to your prospects' provider reaches the primary inbox. In Warmerly's dashboard, an average score of 80 or more with 90% or more of warmup email in the inbox reads as healthy.
What is a good email warmup health score?
Warmerly's dashboard treats an average of 80 or more as healthy and flags anything under 50 as needing attention. Other tools score differently, so compare a number only against the tool that produced it. A score that holds for several days matters more than one high reading.
Why is my warmup score high but my campaigns land in spam?
The score measures warmup traffic between mailboxes in the warmup pool. Campaigns go to strangers, and list quality, content, volume and authentication decide where they land. Check SPF, DKIM and DMARC, send a small verified batch first, and watch Google Postmaster Tools.
Can I trust an inbox placement test?
Use it as a spot check. One test is one moment in time with a small sample, and a test that has no independent seed mailboxes is less reliable than one sent to mailboxes you do not control. Repeat it over several days before you rely on it.
How often should I check my warmup stats?
Look at the trend weekly rather than daily, and check after any change to volume, domain or authentication. Daily readings swing, and reacting to each swing is how people end up changing too much at once.