A freshly registered domain is a blank file at every mailbox provider. Nobody has seen it send, nobody has marked it as spam, nobody has replied to it. That blank file is both the opportunity and the risk: the first few hundred messages you send will write most of its early reputation, and a bad first impression is far slower to repair than a good one is to build.
This is an operating plan for those first 30 days. It is dated from the day you buy the domain, it tells you what to look at each week, and it is explicit about when to stop and wait. The numbers are rules of thumb that work for most cold senders, not laws. If your own data disagrees with them, trust your data.
Day 0: buy, configure, and wait for DNS
Everything on day 0 is setup. Nothing gets sent to a prospect.
- Buy a secondary domain. Never cold email from your primary company domain. Pick a close variant (a different TLD or a short prefix) that a prospect would still recognise as you.
- Publish authentication. MX, SPF, DKIM and a DMARC record at
p=nonewith a reporting address. The pre-send DNS checklist walks through all eight records. - Redirect the root domain to your real website so anyone who types it in lands somewhere legitimate.
- Create the mailboxes with real names, profile photos and signatures. Two to three mailboxes per domain is a common ceiling.
- Verify everything with the SPF and DKIM checker before you turn anything on.
- Start warmup on every mailbox once the records resolve.
DNS changes can take anywhere from minutes to a day or two to show up everywhere, so do the setup early and check again the next morning.
The plan at a glance
Volumes below are per mailbox, per day. Warmup volume refers to automated warmup conversations; cold volume is real prospect email.
| Window | Warmup volume | Cold volume | Main thing to watch |
|---|---|---|---|
| Days 1 to 7 | Starts low (around 5 to 10), rises gradually | None | Authentication passing, warmup mail landing in inbox |
| Days 8 to 14 | Climbing toward 20 to 30 | None | First inbox placement test, blacklist check |
| Days 15 to 21 | Held steady | 5 to 15, hand-picked list | Bounce rate, replies, any spam complaints |
| Days 22 to 30 | Held steady or tapered slightly | Ramp toward 25 to 40 | Placement trend, reply rate per mailbox |
If you want to model the ramp for a specific number of mailboxes and a target daily volume, the warmup calculator does the arithmetic.
Week 1: prove the plumbing works
The only goal this week is to confirm that mail from the new domain is accepted, authenticated and delivered. Send one test message from each mailbox to a personal Gmail and a personal Outlook address, open the original headers and check that SPF, DKIM and DMARC all show pass. A header analyzer makes this quicker than reading raw headers by eye.
Leave warmup running and resist the urge to "just send a few" to prospects. A domain that is a few days old and already sending cold outreach is exactly the pattern filters are built to catch.
Week 2: measure before you send
By now each mailbox has a short history of normal-looking conversations. Before any prospect sees a message, get a baseline:
- Run an inbox placement test. Send a realistic version of your first campaign email to a seed list across Gmail, Outlook and other providers. Our guide on running an inbox placement test covers how to read the results.
- Check blacklists for the domain and, if you are on a dedicated IP, the IP too.
- Read your first DMARC aggregate reports. Look for any source sending as your domain that you do not recognise, or any of your own mail failing alignment.
If placement is poor at this stage, it is a setup or content problem, not a volume problem, because you have barely sent anything. Fix it now.
Week 3: the first real sends
Start with your best list, not your biggest. Verified addresses, tightly targeted, ideally people with a plausible reason to want the email. Run every address through an email validator first, because early bounces are one of the fastest ways to damage a new domain.
Keep cold volume low, somewhere in the 5 to 15 per mailbox range, and keep warmup running alongside it. Write plain, short emails with no attachments, no images and at most one link. Replies matter more than anything else this week: a reply is the clearest positive signal a recipient can send, and early replies do a lot of work for a new domain.
Week 4: ramp with a hand on the brake
If week 3 looked clean, raise cold volume in steps of a few emails per mailbox every two or three days rather than doubling overnight. Watch the trend, not single days. One bad afternoon is noise; three days of rising bounces or falling placement is a signal.
By day 30 a healthy mailbox is usually somewhere in the range of 25 to 40 cold emails a day. Some teams go higher. Most of the trouble comes from teams that tried to go higher in week 3.
Signals that mean slow down
Pause the ramp, or drop back to the previous week's volume, if you see any of these:
- Bounce rate above roughly 2% on a campaign. Check the codes; our bounce code reference explains which ones are list problems and which are reputation problems.
- Any measurable spam complaint rate. Google asks bulk senders to stay below 0.3% and recommends aiming under 0.1%. For a cold domain, treat any upward movement as a warning.
- Placement tests sliding from inbox toward spam at one provider, especially Microsoft, which often reacts faster to new senders.
- Deferrals such as 421 or 4.7.x temporary failures that keep repeating.
- A blacklist listing on the domain or sending IP.
- Replies drying up while sends stay flat. That often means mail is quietly landing in spam.
Slowing down costs you a few days. Pushing through these signals can cost you the domain.
After day 30
A month in, the domain has a short, clean track record, which is a good start rather than a finished job. Keep warmup running at a low level, keep testing placement whenever you change copy or lists, and spread volume across enough mailboxes that no single one carries the load. If you are not sure how many you need, the guide to sizing mailboxes and domains has the maths.
Sendbox runs this loop on each mailbox for you: warmup starts automatically, health and blacklist status are tracked per mailbox, and placement tests are unlimited, so checking before every ramp step does not cost extra. Whatever tool you use, the discipline is the same: measure, then send, then measure again.
