You switched providers. Replies kept falling.
You made the move, set everything up again, and still did not know what was wrong. The migration cost you two weeks and told you nothing.
Someone asked about the drop before you had an explanation.
Your boss or your client wants to know what happened. You are still trying to work it out yourself, and the answer is due now.
You bought new domains. Then it happened again.
Another warm-up period, more money, more waiting, with no way to know whether any of it touched the cause.
Before you blame yourself
You did everything right.
Every fix you tried was the correct fix. Not one of them could have worked.
Is this you?
01
You opened a ticket. Then you waited.
Forty-eight hours. No answer, no cause, nobody telling you a thing.
Ticket #4812 · open
Auto-reply received
48h · no update
The only reply was the one written before you asked.
02
You warmed for three weeks. The tool said healthy.
Healthy, on a provider your leads are not on.
Warm-up complete
Health 98/100
Pool: healthy
Every tool told the truth about its own piece. None owned the join.
03
You watched the reply rate. It moves last.
By the time it drops, the cause is weeks old.
Week 1: reputation slips
Week 3: placement shifts
Week 5: replies drop
You were not slow. You were reading the last signal in the chain.
WHAT YOU ALREADY TRIED
Ran a placement test
Rewrote the copy
Slowed the daily volume
Every fix was a guess.
Built for you
Does this sound like your week?
Who you are
- You send 5,000+ emails a day.
- You run outbound for clients.
- You build with Claude.
What you juggle
- Hundreds of domains to keep an eye on.
- A spreadsheet for every client’s mailboxes.
What’s at stake
- You never see where your emails actually land.
- Spam, while every dashboard says “fine”.
- Clients leave when delivery slips.
Two or more? This was built for you.
We multiply the outbound effect with your sequencer.
The most researched mailbox infrastructure, paired natively with the sequencers your team already runs.
Distance between your mailbox infrastructure and your sequencer: zero.
Distance between your mailbox infrastructure and your sequencer: zero.
Distance between your mailbox infrastructure and your sequencer: zero.
Distance between your mailbox infrastructure and your sequencer: zero.
Running something else, or mailboxes you bought elsewhere? Connect them anyway. The warm-up pool check and the clones work on any infrastructure, free. Decide about the rest later.
Connect what you run
What you get
You order mailboxes.
You order mailboxes.
We keep the replies coming.
Everything you need to launch, send and get replies, without the usual email headaches.
Automatic DNS setup
SPF, DKIM and DMARC, written per domain and verified before the first send.
Isolated tenant
Your own IPs, your own reputation, your own admin panel per domain. Never pooled.
Pre-warmed, any TLD
Mailboxes arrive warm, on whatever domain extension you want to send from.
Never a dip
Up to 75 inboxes per domain, automatic reconnects, infrastructure we replace for you.
01
Free mailbox insurance
First in the industryInsure your sending against the mailbox you are about to lose.
Full replacement within 30 days.
Even on mailboxes you bought somewhere else.
Triggered before the burn, not after it.
Risk Level, our own signal built from sending data nobody else collects, flags the mailbox ahead of your reply rate on every vendor you use.
We eat the cost when we’re wrong.
If Risk Level misses a call, the replacement is on us. We bet our own margin on its accuracy.
Your volume never dips.
No emergency spend to climb back to where you were.
Risk Level
High
Your mailbox is at risk
We detected a high risk level from your sending data, three days before your reply rate would have shown it.
Days since last reply12 days
Total sends8,432
Risk levelHigh
We've got you covered.
Warm-up in progress
Healthy
Measured from outside the pool, against where your campaign actually sends.
Week 2 of 448% complete
1,240
Emails sent
86
Replies
67%
Inbox placement
02
Warm-up you can finally verify
Research that helped Instantly.ai improve its warm-up pool in 2024.
We compare composition, not volume.
Send 80% to Google while 12% of your warm-up goes there, and three weeks of reputation went somewhere your campaign never lands.
Measured from outside, on any infrastructure.
Your score usually comes from the tool doing the warming. We check it across every provider, any vendor, any sequencer, free, with nothing to move or cancel.
A wrong score comes with a fix.
We route you into a private warm-up pool built for sending.ac and Instantly users.
03
Deliverability
You will know before your client does.
A reply rate that only counts real replies.
Warm-up and out-of-office are counted separately, so the number means what you think it means.
Placement, not a proxy.
Microsoft spam score and actual inbox placement, checked daily. When it breaks, you see why and what to do about it.
Down to the hour, per domain, per sender.
Seven checks on every domain, every day, 28 days deep. Filter to the one domain you are worried about, down to the last sixty minutes.
Deliverability · 7 checks, every day
28 days deep
Healthy
Watch
Broke Tue
SPFDKIMDMARCBlocklistPlacementMXrDNS
What broke: DMARC on try-outreach.co dropped Tue 09:41.
Why: registrar reset.
Do: restore p=quarantine. We already paused the sends.
Flagged 19 days before replies fell.
Every domain gets its own site to save from SURBL.
Drop the redirect. Every outreach domain serves its own static copy.
A workspace per client, one view for you.
Their mailboxes, their domains, their risk levels, walled off from everyone else.
An API for everything, with an MCP server on top.
Point an agent at your account and it provisions the infrastructure while you write the campaign.
Their words, not ours
Real stories. Real inboxes.
Every line below came from someone paying for this. Nothing rewritten, nothing invented.
“I tested sending a link and a GIF in the very first email of a sequence, normally a fast way to get flagged. Still landed in primary. Ran it across a few domains to check it wasn’t a fluke, same result each time.”
Saief Tissaoui
Running sending.ac on Azure inboxes
“Can confirm. We actually tested them, and performed next to Winnr the best.”
David Lehnert
Founder, Wyngman
“You guys have the smoothest UX/UI of all the inbox resellers I’ve purchased from. And I’ve worked with ALL of them.”
SP
Sergio Perea
Inbox buyer
“Not gonna believe this but last night in my dream I was at the shops and there were sending.ac mugs for sale.”
A customer
By text message, unprompted
“I tested sending a link and a GIF in the very first email of a sequence, normally a fast way to get flagged. Still landed in primary. Ran it across a few domains to check it wasn’t a fluke, same result each time.”
Saief Tissaoui
Running sending.ac on Azure inboxes
“Can confirm. We actually tested them, and performed next to Winnr the best.”
David Lehnert
Founder, Wyngman
“You guys have the smoothest UX/UI of all the inbox resellers I’ve purchased from. And I’ve worked with ALL of them.”
SP
Sergio Perea
Inbox buyer
“Not gonna believe this but last night in my dream I was at the shops and there were sending.ac mugs for sale.”
A customer
By text message, unprompted
Pricing
2 months free on yearly billing
Flexible pricing plans for the best deliverability a dollar can buy.
Choose the plan that fits your needs. Upgrade or downgrade anytime.
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Pick what aged domains to buyYou choose the aged domains yourself, from our pool, before anything is provisioned. They arrive with sending history already on them, so there is no warm-up window to sit through.
Up to {{ perDomain }} inboxes on 1 domain! How?!Two years of R&D makes this possible. You can safely put more inboxes on fewer domains while keeping industry-leading deliverability. Not possible with other providers.
Skip warmup. Start sending today.
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Agency
Prewarmed
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+ ${{ oneTime3 }} one-time
{{ cycleLabel }}
{{ inboxCount3 }}{{ provInboxes }}
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{{ save3 }}{{ tipThem3 }}{{ tipUs3 }}{{ tipSaved3 }}
Pick what aged domains to buyYou choose the aged domains yourself, from our pool, before anything is provisioned. They arrive with sending history already on them, so there is no warm-up window to sit through.
Up to {{ perDomain }} inboxes on 1 domain! How?!Two years of R&D makes this possible. You can safely put more inboxes on fewer domains while keeping industry-leading deliverability. Not possible with other providers.
Skip warmup. Start sending today.
You get a deliverability expert from day one.
You can get started without a call. But if you prefer 1-1, pick a slot that works for you.
We do relationships, not sales.
You make money, we make money.
Questions
Frequently asked questions
Talk to us, not FAQ.
Most of this is faster over a 15-minute call, with someone who already knows the answer.
Talk to an advisorNo. It sits underneath them. sending.ac provisions and watches the mailbox infrastructure (domains, DNS, IPs, warm-up); your sequencer still writes and sends the campaign. Connect Smartlead, Instantly, PlusVibe or EmailBison and keep your workflow.
No. Mailboxes you bought anywhere else can be connected for free. The warm-up pool check and the deliverability clones both run on outside infrastructure. You only pay for what you provision through us.
Most tools report what already happened. sending.ac measures placement from inside real inboxes, hourly, so a spam-folder shift or a broken DMARC record shows up the day it happens, not three weeks later when a client asks why nobody replied.
Risk Level flags it before your reply rate would have shown it, based on sending data, not a support ticket. On the plans that include it, the mailbox gets replaced within 30 days at no extra cost, even if you bought it elsewhere.
Yes. Every tenant gets its own IPs and its own reputation. You are never pooled with a stranger’s complaint rate the way you would be on a shared sending provider.
Yes. Pricing is per domain and per mailbox, so you can build a plan that mixes both providers with the “Build your own plan” configurator, or run either provider straight on one of the fixed plans.
Yes. There’s a full API and an MCP server. Point Claude, ChatGPT or Cursor at your account with a prompt like “create 4 domains, 3 mailboxes each, start warm-up today” and it provisions while you write the campaign.
Domains, DNS (SPF, DKIM, DMARC) and mailbox provisioning are automatic, so your first domain set can be live the same day you sign up. Warm-up still takes its usual few weeks; we just verify it’s actually working, from outside the tool doing the warming.
Ready when you are
Start sending today
