Email Warm Up: Daily Volumes and DNS Setup

What is email warm up and why is it important?

Email warm up is the period when a new or long-idle sending domain goes from no history to a steady daily volume in small, planned steps. Mailbox providers such as Gmail and Outlook.com judge a sender mostly on the domain's track record. They look at how many messages arrive, how many bounce and how many recipients mark them as spam. A domain with no history gives them nothing to judge. A sudden burst of several hundred cold emails from it looks just like a freshly registered spam domain. Warming up gives receiving servers a small, consistent sample first. Google's sender guidelines set a limit worth knowing from day one: user-reported spam should stay below 0.3% in Postmaster Tools, and Google recommends under 0.1%. Once a domain sends 5,000 or more messages a day to Gmail addresses, Google treats it as a bulk sender. It then also has to publish DMARC and support one-click unsubscribe under RFC 8058. Warming up doesn't guarantee inbox placement, because the receiving server decides that. But if you skip it, those servers have no history to go on.

How many emails a day during an email warm up, and for how long?

No mailbox provider publishes an official warm-up schedule, so every number below is a rule of thumb from practice, not a standard. Many cold-outreach teams use a cautious ramp like this for a fresh domain:

1. 1 Week 1: around 20 messages per day, sent to the contacts most likely to recognise your name.
2. 2 Week 2: around 40 per day, but only if bounces stay low and no spam complaints come in.
3. 3 Week 3: around 80 per day, still to addresses you've verified.
4. 4 Week 4 onward: increase by no more than about double per week until you reach your target volume.
5. 5 Any time bounce or complaint figures rise, hold your current volume or step back for several days.

Two things matter more than the exact figures. The first is consistency: 40 a day for five days looks better to providers than 200 on Monday and nothing after. The second is list quality. Warming up with unverified addresses produces hard bounces, which are permanent SMTP 5xx rejections such as 550 'user unknown'. Those count against the domain from the very first send. Domain age matters too. A domain registered last week starts with less trust than one that has sent normal business mail for months.

Which DNS records do you need before an email warm up?

If the domain isn't authenticated, the weeks you spend warming it up are wasted. The reputation you build isn't tied to an identity receivers can verify. Set up these records before the first message goes out:

• SPF (RFC 7208): one TXT record at the domain root that lists Brevo and every other service sending for you. A domain may have only one SPF record, and it can trigger at most 10 DNS lookups.
• DKIM (RFC 6376): the key Brevo gives you, published under its selector, so messages are signed with your domain rather than a shared one. 2048-bit keys are the current recommendation.
• DMARC (RFC 7489): a TXT record at _dmarc.yourdomain. Start with p=none and a rua address so you receive aggregate reports.
• Alignment: for DMARC to pass, the domain in the visible From address must match the DKIM signing domain or the SPF domain.
• Verification: check every record with dig or nslookup before sending. A typo in a TXT record fails without any error message.

If your domain is registered at GoDaddy, our guide to GoDaddy DKIM setup for Brevo explains the Host field quirks. For Google Workspace domains, read G Suite DKIM for Google Workspace and Brevo. Google's own key doesn't sign mail sent through Brevo.

How does EmailFlow OS fit into an email warm up?

EmailFlow OS doesn't replace a warm-up and doesn't run one for you. What it decides is where the mail comes from. You record one video and upload it to EmailFlow OS. You connect your own Brevo account and sending domain, and you import your prospect list into EmailFlow OS. EmailFlow OS then makes a personalised version of that recording for each recipient (per person, not per company). It sends every version from your own inbox, through your Brevo account and your domain. Nothing goes out through a shared platform sender. So every message adds to the reputation of the domain you're warming, and the bounces and complaints show up in your own Brevo account. The history you build during warm-up stays with a domain you own and can keep using. In practice, the lever you control is how many recipients each imported prospect batch contains. If you're in week one of your ramp, import a batch sized for week one, not your whole database.

What are the steps to send personalised video emails with EmailFlow OS?

The sequence is short. You do each step once per campaign:

1. 1 Record a single video message for your target audience.
2. 2 Upload the video to EmailFlow OS.
3. 3 Connect your Brevo account and your sending domain in EmailFlow OS.
4. 4 Import your prospect list into EmailFlow OS.
5. 5 EmailFlow OS personalises the video for each recipient and sends each version through your Brevo account.

During warm-up, step 4 is where you need discipline. If you import your full prospect database on day one, the whole list is ready to send, and a fresh domain shouldn't send to all of it. Split the list into batches that match your ramp, and start with recipients whose addresses you've confirmed. Keep the email itself light as well. Gmail clips HTML messages larger than 102 KB, and a clipped message hides the footer with your unsubscribe link. Our cold email format guide covers what belongs in that message.

Why use your own Brevo account and sending domain?

Providers track reputation by sending domain, and at the IP level by the infrastructure the mail comes from. When mail goes out through a shared platform address, receiving servers credit the history to that shared identity, and other senders' behaviour gets mixed in with yours. EmailFlow OS sends through your own Brevo account and domain instead, which matters during warm-up in three ways. First, the DKIM signature carries your domain (d=yourdomain), so you can actually set up and check DMARC alignment. Second, your DMARC aggregate reports, which providers usually send once a day, list every source sending as your domain, including Brevo. That lets you spot a misconfigured record quickly. Third, if you stop using EmailFlow OS, you keep the domain, the Brevo account and the reputation you built. What doesn't change: Brevo's account policies still apply to you, and a poor list damages your domain just as fast as anyone else's. Because you own the sending setup, every result traces back to your own sending, good or bad.

What goes wrong during an email warm up?

Most stalled warm-ups have a cause you can find in the bounce logs or DNS records. These are the common ones:

• Volume spikes: going from 20 to 500 messages in one day. Receiving servers respond with temporary 4xx deferrals and rate limits.
• Unverified lists: dead addresses return permanent 5xx bounces, and each one counts against a domain that has little history to offset it.
• Duplicate SPF records: two v=spf1 records on one domain produce a PermError, so SPF fails for every message.
• Automated warm-up pools: tools that trade synthetic mail between mailboxes create activity no real prospect ever sees. They do nothing about complaints from the people you actually write to.
• Ignoring EU rules: GDPR Article 14 says people whose data you didn't collect from them must be informed within one month at the latest. In Germany, UWG §7 generally requires prior consent for advertising by email.

Whether you meet those rules depends on how you run your outreach. No sending setup handles it for you. Follow-ups also count toward your daily volume, so plan them into the ramp. Our post on cold email follow-up timing and threading covers the spacing and limits.

Questions people ask

? How long does an email warm up take?

No provider publishes an official duration. A common rule of thumb for a new domain is 4 to 6 weeks: start at about 20 messages a day and roughly double the volume each week while bounces and complaints stay low. If Google Postmaster Tools shows a spam rate approaching 0.3%, stop increasing and hold your volume until it drops.

? Does EmailFlow OS warm up my domain automatically?

No. EmailFlow OS takes one recording, personalises it for each recipient on the list you import, and sends each version through your own Brevo account and domain. You set the warm-up pace by sizing each imported batch, for example about 20 recipients a day in week one rather than your entire list.

? Do I need DMARC before I start warming up a domain?

Yes, in practice. Google and Yahoo require DMARC from senders sending 5,000 or more messages a day, and p=none is the minimum policy. Publishing it from day one, with a rua address, gets you daily aggregate reports that show whether SPF and DKIM are aligned for mail sent through Brevo.

? Should I warm up my main company domain or a separate one?

Many outreach teams use a secondary domain or subdomain for cold email, so a warm-up mistake doesn't affect mail like invoices or support replies. The trade-off: a new domain starts with no history and needs the full ramp. Your main domain has history but carries everything your company sends.