Deliverability
The part nobody shows you
Outbound lives or dies on whether the email arrives. Most tools tell you they handle deliverability and leave it there. Here are the actual mechanics — the records, the caps, the ramp, the numbers — so you can judge them instead of trusting them.
Your real domain never sends a cold email
Outbound goes out from separate domains, registered and owned in an account we control, set up specifically for your campaigns. Your company domain — the one your invoices, your contracts and your existing customers depend on — is never part of the sending pool.
This is the single most consequential decision in outbound infrastructure, and it is not reversible after the fact. A burned primary domain takes months to recover and takes your normal business mail down with it.
We own the domains rather than renting them from a sending vendor, which means they stay yours to move. Mailboxes are real Google-hosted accounts, not relay addresses.
Written into every sending domain, before it sends anything
- SPF
- Declares which servers may send as this domain. Without it, mailbox providers have no way to tell your mail from a forgery.
- DKIM
- Cryptographically signs every message, so the receiving server can prove it wasn't altered in transit.
- DMARC
- Published at p=reject — the strictest policy there is. Anything failing SPF and DKIM in your domain's name is refused outright, not quarantined.
- MX
- Routes replies back to a real, monitored mailbox — not into a void. A sending domain that can't receive is a spam signal in itself.
You never touch a DNS panel. There is no setup checklist to get wrong.
Volume discipline, enforced by the system
Every limit below is applied by our servers to every account. None of them is a setting you can turn up on a good week — which is the point. The most common way outbound dies is someone deciding, once, that the caps are too conservative.
20 → 30
Warmup ramp
A new mailbox opens at 20 sends a day and climbs by 1 daily over two to three weeks, holding real conversations at a 30% reply rate with read behaviour emulated.
30/day
Hard ceiling per inbox
The absolute maximum any single mailbox will send in a day, no matter how large the campaign behind it is.
24/day
What we actually plan
Fleets are sized at 24, leaving 20% headroom unused on purpose — for the ramp, for bounces, for schedule variance.
3 max
Inboxes per domain
Enforced server-side: the system refuses to create a fourth mailbox on a domain. Volume spreads across more domains instead of stacking onto one.
Sending is then spread across the whole fleet rather than run through one mailbox at a time, and campaigns send on weekdays — matching how the people receiving them actually work.
How many inboxes do you actually need?
This runs the same sizing rule the product itself uses when it recommends your setup — so the answer here is the answer Boostie would give you inside the app.
Follow-ups per contact
Every follow-up is a send, so it counts against inbox capacity just like a first email does.
What that needs
- Emails per month
- 1,500
- Inboxes
- 3
- Sending domains
- 1
- Sends per day across the fleet
- 72
Sized at 24 sends per inbox per day across 22 sending days — 528 emails a month each — and capped at 3 inboxes per domain. The hard ceiling is 30 a day; we plan 20% under it on purpose, so a busy week never pushes a mailbox to its limit.
A bad address is never sent to
Bounce rate is the fastest way to lose a domain, and it is almost entirely preventable. Every address is verified before it can enter a sending queue. Anything that comes back invalid, spam trap, abuse, do-not-mail is excluded structurally — the query that decides who gets an email cannot return them, so there is no path by which one gets sent to by mistake.
Verification is re-checked every 30 days. And if an address turns bad in the window between being queued and being sent, it is pulled back out of the queue rather than sent anyway.
- Before sendEvery address verified; unsendable verdicts structurally excluded
- After queueingAn address that turns bad is released, not sent
- On replyAsk to stop and the domain is suppressed — permanently, across your campaigns
- AlwaysOne person is never emailed by two of your campaigns at once
- Every 30 daysVerification re-checked so stale data never drives a send
Domains are consumables, and we treat them that way
Any honest account of outbound admits that sending domains wear out. Ours are built to be replaced: every domain moves through a defined lifecycle, and the system knows which stage each one is in. Health is read back from every mailbox every hour — warmup state and a health score, stored as our own data — so a problem shows up as a state change rather than as a quiet collapse in reply rate three weeks later.
- 1
Warming
Registered, DNS in place, ramping. Two to three weeks before it carries real volume.
- 2
Active
Carrying its share of sending, health checked every hour.
- 3
Degraded
A recoverable dip. Volume comes off it while it recovers — or it gets retired.
- 4
Retired
Burned and rotated out. It never sends again, and a fresh domain takes its place.
Questions people actually ask
- Do you send from my company domain?
- No — and you shouldn't want us to. Outbound is sent from separate domains we register and own on your behalf, so your primary domain's reputation is never exposed to it. If a sending domain ever burns, it is retired and replaced; your real domain was never involved.
- Is SPF, DKIM and DMARC set up automatically?
- Yes. Every sending domain gets its full authentication record set written at provisioning — SPF, DKIM, DMARC and MX — before a single email leaves it. DMARC is published at p=reject, the strictest policy available. There is nothing for you to configure and no DNS panel for you to log into.
- How long is warmup, and can I skip it?
- Two to three weeks, and no. A new mailbox starts at 20 messages a day and climbs by 1 a day, exchanging real conversations at a 30% reply rate with read behaviour emulated. The ramp is applied identically to every mailbox and isn't a setting — a mailbox that skips warmup damages the domain it sits on, and that domain is shared with your other inboxes.
- How many emails does one inbox send per day?
- 24 in planning, against a hard ceiling of 30. We deliberately size fleets on the lower number so ordinary variance — a busy week, a re-send, a schedule change — never pushes a mailbox to its limit. That works out to 528 emails a month per inbox.
- Why only three inboxes per domain?
- Because inbox count per domain is one of the clearest volume signals a mailbox provider reads. Packing ten mailboxes onto one domain multiplies throughput and multiplies the blast radius when it goes wrong. Three is enforced by our servers, not suggested — the system refuses to create a fourth.
- What happens to invalid addresses?
- They are never emailed. Every address is verified before it enters a sending queue, and anything coming back invalid, spam trap, abuse, do-not-mail is structurally excluded from selection — not filtered by convention, but refused by the query that picks who gets an email. Verification results are re-checked every 30 days, and a lead whose address turns bad after it was queued gets pulled back out before it sends.
Set up once, correctly, without touching DNS
Boostie buys the domains, writes the records, warms the mailboxes and sizes the fleet for the volume you asked for. You approve the spend; everything above happens on its own.
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