You switch providers. Replies keep dropping.
You make the move, set everything up again, and still don’t know what’s wrong. The migration costs you two weeks and tells you nothing.
Before you blame yourself
You’re doing everything right.
Every fix you tried is the correct fix. None of them could have worked.
Is this you?
You open a ticket. Then you wait.
Forty-eight hours. No answer, no cause, nobody telling you a thing.
Ticket #4812 · open
Auto-reply received
48h · no update
You warm up for three weeks. The tool says you’re fine.
Your leads are on Gmail. Your warm-up went to Outlook.
Warm-up complete
Health 98/100
Pool: healthy
Reputation you build with one provider does not carry to the other. No tool checks that.
You watch the reply rate. It’s the last thing to move.
By week 5 you notice. It started in week 1.
Week 1: reputation drops
Week 3: mail lands in spam
Week 5: replies dry up
Your mail hits spam first, so fewer people see it. The replies stop weeks later.
WHAT YOU TRY
Run a placement test
Rewrite the copy
Slow the daily volume
Every fix is 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 is built for you.
Get more replies out of the sequencer you already run.
The most researched mailbox infrastructure, paired natively.
IntegrationAuto reconnect and replace
sending.ac mailboxes connect to Smartlead natively, reconnect on their own and get replaced when one burns, so the volume your campaigns plan for keeps going out.
See the Smartlead page
IntegrationPremium warm-up pool
sending.ac mailboxes connect to Instantly natively, qualify for the premium warm-up pool on their reputation, and get their warm-up checked against where your campaigns actually send.
See the Instantly page
IntegrationDay 1 first domains live
Order domains and mailboxes, let DNS get written and verified for you, and connect them to PlusVibe natively. The first domain set can be live the day you sign up.
See the PlusVibe page
Integration7 domain checks a day
sending.ac mailboxes connect to EmailBison natively, and every domain behind them gets seven checks a day, hourly placement data and a reply rate that counts only real replies.
See the EmailBison page- In your sequencer in secondsPre-warmed mailboxes, paired natively and ready to send.
- Disconnects reconnect themselvesAutomatic reconnects, so the sequencer keeps sending.
- Placement checked every dayAgainst deliverability data from 6M domains, per domain, per sender.
Running something else, or mailboxes you buy 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.
Free mailbox insurance
First in the industryInsure your sending against the mailbox you’re about to lose.
Full replacement within 30 days.
Even on mailboxes you buy 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 detect a high risk level from your sending data, three days before your reply rate shows 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
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 go 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.
Deliverability
You’ll 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’re 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 fall.
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 comes from someone paying for this. Nothing rewritten, nothing invented.
“[His line from the recording goes here, in his own words.]”
Previous CRO of Inboxkit
Michael Gardiner
Case studyGetSales
Case studyJohannes
Case studyLeevi
Case study
David LehnertFounder, Wyngman
LinkedIn
Can confirm. We actually tested them, and performed next to Winnr the best. Good on Yannic Schwock
A customerBy text message, unprompted
Text
Yo Yannic,
Not gonna believe this but last night in my dream I was at the shops and there were sending.ac mugs for sale!
So I thought I text you today and see how everything is going!
Se
Sergio PereaInbox buyer
Message
Btw, you guys have the smoothest UX/UI of all the inbox resellers I’ve purchased from.
And I’ve worked with ALL of them.
Best,
Sergio Perea
Saief TissaouiPosted in General discussions
Community
I tested sending links + GIFs on first #1 cold email (usually a death sentence) and still landed in primary
Been running sending.ac (Azure based inboxes) for my domain/inbox infra for a few months now. Setup was fast, DNS and DKIM handled automatically, and each domain runs on its own isolated tenant so a burned domain stays contained.
The thing that actually surprised me: 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.
Still plugging everything into ReachInbox the same as always, just wanted to share the infra side since it’s held up better than I expected. Hope it helps!
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.
{{ reach2 }}{{ tipReach }}
Popular
Growth
Prewarmed
${{ p2 }}
/ mo
+ ${{ oneTime2 }} one-time
{{ cycleLabel }}
{{ inboxCount2 }}{{ provInboxes }}
{{ add2 }}
{{ save2 }}{{ tipThem2 }}{{ tipUs2 }}{{ tipSaved2 }}
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’s 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.
{{ reach3 }}{{ tipReach }}
Agency
Prewarmed
${{ p3 }}
/ mo
+ ${{ oneTime3 }} one-time
{{ cycleLabel }}
{{ inboxCount3 }}{{ provInboxes }}
{{ add3 }}
{{ 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’s 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.
Need more than the Agency plan?
Pick any count from 1,100 mailboxes and see the price before you pay.
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 buy 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 the past. 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 replies.
Risk Level flags it before your reply rate shows 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 buy it elsewhere.
Yes. Every tenant gets its own IPs and its own reputation. You’re never pooled with a stranger’s complaint rate the way you’d be on a shared sending provider.
Not yet. Google mailboxes are on a waitlist for now, so every plan runs on Azure. When Google opens, you’ll be able to split a plan between both providers.
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
