There is a specific moment where a sending domain looks finished and is not. The banner says day 21 of 21. The daily cap says 100. Both are correct, and neither is enough on its own to tell you what is happening.
This is part three of the deliverability field guide. Part one covers warming a new sending domain, which is the ramp itself. This one is about the limit that sits underneath it and why a calendar is the wrong instrument for measuring it.
A calendar cannot earn reputation
Mailbox providers do not ask how long your domain has existed. They ask what it has done. Gmail and Microsoft build their picture of a sender from delivered messages, opens, replies and complaints, all of which require someone to actually send something. A domain registered eight months ago that has never sent a message has no reputation at all. It has an age.
So a warmup schedule expressed purely in days is measuring the wrong variable. It is a reasonable proxy when someone follows the schedule, because following the schedule means sending, and the sending is what does the work. It stops being a proxy the moment someone stops sending and lets the clock run.
Which leaves a gap between what a schedule assumes and what a domain actually did.
The two gradients
SEMAOS gates a new custom sending domain on calendar age and on cumulative sends, independently, and enforces whichever of the two is more restrictive.
| Phase | By calendar age | By cumulative sends | Daily cap |
|---|---|---|---|
| Foundation | days 0 to 7 | up to 800 | 100 |
| Ramp | days 8 to 14 | up to 4,300 | 500 |
| Scale | days 15 to 21 | up to 18,300 | 2,000 |
| Completed | day 22 onward | over 18,300 | your plan limit |
Read a row across and the two columns are alternatives, not requirements. A domain sits in the foundation phase if it is younger than eight days or if it has sent 800 messages or fewer. Whichever gradient is more restrictive is the one that sets the cap.
Age can only hold you back early, since it runs out after 22 days whatever you do. Volume can hold you back indefinitely.
Why the volume numbers are not arbitrary
The thresholds look like they were picked out of the air. They were not. Each one is the exact capacity the age ramp would have delivered by the end of that phase:
- 800 is 8 days at 100 a day.
- 4,300 is 800, plus 7 days at 500 a day.
- 18,300 is 4,300, plus 7 days at 2,000 a day.
So the two gradients are one policy expressed two ways, rather than two differently shaped curves fighting each other. A domain that follows the age ramp and sends its full allowance every day arrives at day 22 with roughly 18,300 messages behind it, and both gradients complete at the same moment. Nothing is being held back twice.
A domain that sends less than its allowance arrives at day 22 with less history, and the volume gradient is what notices.
The case this exists for
Take a domain that is 33 days old and has sent around 400 messages in its life.
On age alone it is finished. Day 22 passed eleven days ago, so an age-only check clears it for the full plan limit. On volume it has sent 400 of the 800 it needs to leave the opening phase, so it is barely half way out of foundation. The effective cap is 100 a day.
An age-only warmup would have handed that domain an unlimited allowance on roughly five percent of the sending history a completed ramp represents. Not because anything went wrong, but because a calendar has no way to know the difference between a domain that ramped and a domain that idled.
This is why a progress readout that only counts days is worse than no readout. "Day 21 of 21" next to a 100 a day cap does not look like two measurements of different things. It looks like a bug, and the person reading it is left to guess which half to believe.
What this means if you are warming a domain now
Send steadily rather than in bursts, because cumulative volume only moves when you send. A quiet week does not undo anything, since the total never goes down, but it buys you nothing either while the calendar carries on without you.
If you need a particular daily volume by a particular date, work backwards from the cumulative total instead of from the number of days. Reaching 4,300 sends is what opens the 2,000 a day step, and no date does that on its own.
And when the day count and the daily limit disagree, believe the daily limit. That is the number deciding whether today's campaign goes out.
When they disagree, and which one wins
A tie resolves to age. When both gradients point at the same phase there is nothing to explain, and for a genuinely young domain the day count is the more meaningful progress number: it tells you the soonest this can possibly be over.
When they disagree, the interesting question is which one is binding, because that is the one you can do something about. If age is binding, the answer is patience. If volume is binding, the answer is to send. Those are opposite instructions, which is exactly why a single progress bar cannot represent both.
Everything above is about the cap this platform enforces, which is a floor on good behaviour rather than a guarantee about placement. A domain inside its limits can still land in spam if the list is bad or the copy is wrong. If your placement is falling while your volume is legal, that is a different investigation and diagnosing a single provider is where it starts. The product tour shows where the domain status and its current cap appear.
FAQ
Why does my domain say day 21 of 21 and still cap me at 100 a day?
Because age is not the constraint that is binding. If the domain has sent fewer than 800 messages in total it is still in the foundation phase on the volume gradient, and the lower of the two caps is the one enforced. The day counter is telling the truth about the calendar and nothing about the reputation.
Can I finish a warmup faster by waiting longer before I start?
No, and it is worth being clear about why. Age alone will carry a domain to the completed phase after 22 days, but the volume gradient will still hold it wherever its cumulative send count puts it. An idle month buys you nothing that a sending month would not have bought you as well.
Does a gap in the middle of a ramp set me back?
It does not reset anything, because cumulative sends only ever go up. What it does is stop progress: the calendar keeps advancing while the volume total does not, so you arrive at day 22 with the volume gradient still holding the cap where it was.
What happens when the two gradients agree?
Nothing worth explaining, which is why a tie resolves to age. When both point at the same phase, the day count is the more useful progress number for a young domain and that is what gets shown.