Provision
domains, mailboxes, DNS and authentication, reachable from your own sequencing tool over SMTP and IMAP.
Plimsoll is sending infrastructure with a ceiling you cannot raise.
Every domain gets a published daily maximum and a 21-day ramp. A model reads the replies no header rule can, and the ramp holds on anything that might be a complaint. No button moves the ceiling.
No card required.
The sequence worked for nineteen days. On day twenty the reply rate halved, and by day twenty-four four domains were in spam for every recipient on Microsoft 365.
Nothing had said no. The tooling offered more mailboxes, warmed them, and let the daily volume go up in the same week two people asked to be removed.
$90
per domain per month, at one domain or forty
21 days
published ramp, the same schedule for everyone
1 in 6
replies no header can classify, read by a model that holds the ramp rather than guess
Product
The reply stream decides the ceiling, and most of it is unreadable by rule
Ramp
a published 21-day schedule to the domain ceiling, identical for every customer and visible before you buy.
Match by header
bounces, vacation auto-responders and delivery failures carry structure, and rules take all of it.
Classify the rest
one reply in six is free text, and a model reads it, scores it and quotes the sentence it decided on.
Hold, do not guess
under the floor the reply stops that domain's ramp and waits for a named reviewer.
Suppress on request
a removal request is suppressed across every domain you run, immediately, and cannot be lifted.
Get started
The first three weeks, including the boring half
Most of it is DNS, and none of it is faster if you pay us more.
Steps 01–03
- 01Day one, domainshand over the domains you own or let us register them, and we set DNS and authentication.
- 02Day one, the backfillmonths of existing reply history are read in one batch so day two is not a blank slate.
- 03Day two, connectpoint your sequencing tool at the mailboxes over SMTP and IMAP. Nothing runs in our interface.
Steps 04–05
- 04Days two to twenty-twothe published ramp, in increments you can read in advance, holding on any day with a held reply.
- 05Day twenty-threethe domain sits at its ceiling and stays there. This is the last thing that changes.
A decision
The ceiling is enforced against you, not configured by you
Every tool in this category ships a daily cap and a field to edit it. In practice the field is edited on the day the number is behind, which is also the day the complaint rate is climbing.
So there is no field. Support cannot raise it, an annual contract does not raise it, and asking loudly does not raise it either.
The cost is straightforward: we lose every buyer who wants to send more this quarter, which on some weeks is most of them, and we cannot compete on any page that compares capacity.
Where replies are read, and what we never take
- Free-text replies classified on Azure OpenAI in West US 3, nothing retained
- Reply bodies deleted after 180 days; the classification is kept
- Prospect lists are never uploaded, stored or enriched here
- Sending and the reply store on AWS us-west-2
- Suppressions are permanent and survive cancellation
- Every reviewer read of a held reply is logged in your export
Reply bodies are the recipient's own words, which is why they do not leave the United States.
Not for
What you will not get here
- No unlimited plan, at any price. The ceiling is not a tier.
- No sequencer. Bring your own tool; there is no editor and no scheduling here.
- No list, ever. We do not sell, enrich or verify prospect data.
- No inbox placement promise. We guarantee the ceiling and the classification, not the inbox.
- No warmup theatre. The ramp is published and it is the same for everyone.
- No lifting a suppression. An address that asked to be removed stays removed.
Pricing
$90 per domain, per month
Mailboxes included with every domain, not sold by the unit
DNS and authentication setup, and the reply history backfill
Daily ceiling, ramp position, complaint rate and held-reply count by API
Reviewer time on every held reply, at no extra cost
Limits
The numbers that do not move
$90
per domain per month, published
21 days
ramp to ceiling, identical for every customer
1 in 6
replies with no header to classify them by
180 days
reply bodies retained, then deleted
0
ways to raise a domain above its ceiling
FAQ
What people ask before the second domain
Can I pay to raise the ceiling?⌄
No. There is no plan, contract or support ticket that changes it.
What is the ceiling?⌄
It is published per domain type on this page and in the API before you provision anything.
Can I use my own sequencing tool?⌄
Yes, that is the intended setup. We provide mailboxes over SMTP and IMAP and nothing else.
What happens when a reply is held?⌄
That domain stops advancing its ramp until a reviewer reads the reply, usually inside a business day.
Do you register domains for me?⌄
Yes, or you bring your own. Either way DNS and authentication are ours to set up.
Run one domain through the whole ramp for nothing
One work email. No card. Twenty-one days, and you keep the domain either way.
We'll come back within one business day with a straight yes or no.