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Cold outbound gets sent from domains you bought instead of your company domain. Deliverability is the reason why. By the end of this lesson you'll know what decides whether an email lands, what domain jail is, and why cold infrastructure is built the way it is.

📥 What Deliverability Actually Is

Deliverability is one question: did the email land in the inbox. If it went to spam, you didn't deliver.

You can send 50,000 emails, have every one accepted by the receiving server, and deliver almost none of them.

The first thing to accept is that you don't get to decide. Email providers run machine learning models over every message, and those models are heuristics. Good ones, but heuristics. You never know ahead of time whether a given email lands.

So you're not aiming for certainty. You're playing the odds, and everything in this course is about improving them.

🏆 Domain Reputation Is Most of It

A few things feed the decision, and they are not weighted anything like evenly. Domain reputation is the 80/20, and it's the thing this whole course is built around protecting.

Every email provider keeps a running judgment on the domains that send it mail. This isn't a setting you configure and it isn't a number you can look up. It accumulates.

Every message you send moves the needle, based on what the person receiving it does next. They can open it, reply to it, click a link, ignore it, delete it, or report it.

The critical part is where that judgment attaches:

• Reputation attaches to the domain, not the address in front of it. Every address on your domain shares one reputation
• A brand new address inherits whatever standing the domain already has. Spin one up this afternoon and it starts life with the domain's history, good or bad
• Providers judge the domain because they know you can spin up thousands of addresses in an afternoon. The address is not a meaningful unit to them

Which cuts both ways. A good reputation is shared by everyone sending from that domain. So is a bad one: you can't quarantine a bad campaign to one mailbox.

📜 The Rest of the List

After the domain comes your IP, which providers used to weight far more heavily than they do now. Domain reputation has overtaken it.

Underneath all of it sit SPF, DKIM, and DMARC. Those are DNS records, DNS being the internet's address book, and all three do roughly the same job: they prove the email came from where it claims to have come from. Think of the return address and the postmark on an envelope.

If you're on Google Workspace or Microsoft, your IT admin set these up years ago and you've never had to think about them. When you buy accounts through Clay, they come configured.

🚨 Domain Jail

What you're trying to avoid is someone opening your email and pressing Report spam or Report phishing.

It takes genuine annoyance to make a person stop what they're doing, click into the menu, and press that button. That's exactly why email service providers weight it so heavily.

Cold outbound is uniquely exposed. Your prospect doesn't know who you are, so there's no relationship to spend and no reason to give you the benefit of the doubt. When a message misses, they're far more likely to press that button than a customer expecting your email would be.

Get enough of those on a domain and the domain is finished. Larry Li, the engineering manager for Sequencer, calls this domain jail, because everything else on that domain goes down with it. The invoices you send from it. Your support replies. The email to your mom about missing dinner on Sunday.

This has happened to real companies. Some early AI outbound tools ran high volume campaigns straight from their customers' primary domains, and that meant weeks of broken business email.

🚐 The Car and the Vans

Your company domain is the car in your driveway. It has to start every single day. It has to be ready Monday morning to take the kids to school and get you to work, and if it breaks down your whole week breaks with it.

You would not use that car to run 500 deliveries a day. You'd rent vans. A bunch of cheap ones, several of them, and you'd run those hard. When one wears out you send it back and rent another. The car in your driveway, the family car, never gets touched.

Same goes for domains. You buy a small fleet of alt sending domains that sound similar to your company domain, run your campaigns through them, and retire them as they wear out. Your real domain stays clean because it was never involved.

The same idea runs one level down. Cold sending infrastructure rotates across many IP addresses instead of pushing everything through a few, so one bad address doesn't drag the rest down with it. Same reason you rent several vans instead of one.

🔥 Warming

One thing about that fleet. A domain you bought on Tuesday has no reputation at all, and no reputation is its own kind of problem.

Warming is like building a credit score, but for email. You show up with no history, so nobody extends you any trust, and the only way to earn it is to behave well for a while. Good behavior here means you send emails and people write back.

So before a new domain sends a single campaign, it spends weeks trading ordinary looking mail with a pool of other accounts, building a record of normal human traffic. Then when your campaign starts, the volume isn't a spike out of nowhere. It's more of what that domain was already doing.

We recommend two to three weeks of warming.

✅ What Clay Handles

Warming is included, and it doesn't cost you anything extra. It's usually a separate purchase, and in Clay it's on by default for accounts you buy.

That's the pattern for the rest of it too:

• The DNS records come configured on accounts you buy
• IP rotation happens without you asking for it
• Global analytics gives you one place to track bounce rate, which is the leading indicator of a domain's reputation

So far that's four things that affect deliverability: domain reputation, dynamic IP addresses, not getting reported for spam or phishing, and warming.

🎚️ Four More Things That Move the Odds

Everything else in this course sits downstream of those four, but four decisions do real work on your odds.

1. Send time - Weekdays, business hours, with a gap between sends, so you look like a person working through a list instead of a machine emptying a queue
2. Volume - Around 20 emails a day per inbox. That's the number everyone wants to negotiate with
3. Plain text, especially on the first email - That first message sets how a provider reads you, so send it plain and save the formatting for later, if you use it at all
4. Vary your copy - 10,000 word for word identical emails read like bulk mail no matter how good the writing is. In the Sequencer you can use AI snippets to change whole sections of an email, or spintax to rotate individual words, so no two sends match exactly

😅 This Is Hard, Even for the Biggest Senders

Go look in your spam folder at some point today. You'll find mail in there from companies you actually signed up for. Google, Stripe, and Clay all land there.

If the biggest senders on earth can't land every single message, you're going to miss some too.

🚀 What's Next

You now know what deliverability is, why domain reputation carries most of the weight, what domain jail costs a business, and why cold outbound runs on a fleet of alt domains that Clay warms for you.

Next, we go rent the vans. We'll walk the whole flow for buying domains and inboxes inside Clay

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