Your emails are not being ignored. They are not arriving.

A founder shows us a campaign with a 0.4 percent reply rate and asks whether the copy is wrong. Before we read a single subject line, we check where the mail landed. About half the time the copy was fine and roughly a third of the sends never reached an inbox at all.

Deliverability is the part of outbound nobody buys and everybody pays for. It has no dashboard in most sending tools, it fails silently, and it degrades over weeks rather than breaking in one visible moment. A campaign can look busy in the reporting screen while Microsoft quietly files every message in Junk.

This post lays out what actually decides inbox placement for a European B2B sender in 2026, in the order the receiving server checks it.

Authentication comes first, and it is binary

Three DNS records decide whether a receiving server will even consider your message. Get them wrong and nothing else you do matters.

Google and Yahoo made bulk-sender authentication mandatory in February 2024, and Microsoft followed for high-volume senders in May 2025. The floor moved. A domain without DMARC now looks like a domain that has never been configured by anyone who sends real mail.

Set DMARC to p=none for the first fortnight so you can read the aggregate reports, then move it to p=quarantine. Leaving it at none forever tells receiving servers you do not care what happens to mail claiming to be from you.

Check SPF with a lookup counter, not by eye. A record that includes three vendors usually breaches the ten-lookup limit, and the failure mode is a soft pass that quietly stops helping.

Never send cold mail from the domain you invoice from

Outbound burns domain reputation. That is not a risk to manage, it is the mechanism working as designed: you are mailing strangers, some will mark you as spam, and the receiving networks will score the domain accordingly. If that domain also carries your invoices, your support replies and your calendar links, you have put the whole company on the same fuse.

Buy separate domains that a human would recognise as yours. If the company is Northgate Analytics on northgate.com, send from northgateanalytics.com or getnorthgate.com. Redirect each one to the main site with a 301 so a curious prospect who types it in lands somewhere real. Do not use a domain that looks like a typosquat.

Two to three mailboxes per domain, and the arithmetic follows from your volume target. At a sustainable 30 sends per mailbox per day, three mailboxes on three domains gives you 270 first touches a day and about 5,600 a month once follow-ups are counted. Most European campaigns need fewer than that.

Warm-up is a calendar item, not a setting

A new domain has no sending history, and a domain with no history sending 200 cold messages on day one reads as a throwaway. The receiving networks want to see volume climb the way a real business grows.

Three weeks before the first real send is the number that surprises people. Budget for it. A client who signs on the first of the month and expects meetings by the fifteenth has bought a timeline that the infrastructure cannot deliver, and pushing the volume to meet it produces a burned domain and no meetings.

What the receiving server reads after authentication

Once your mail is authenticated it enters the part nobody can see. Microsoft and Google both score the message and the sender, and neither publishes the weights. From what we can observe across campaigns, four things move the needle.

Engagement. Replies help most. Opens help a little. Deletions without opening hurt, and spam complaints hurt disproportionately. One complaint per thousand sends is the ceiling Google states publicly; above that, placement degrades fast.

Content signals. Tracking pixels, link shorteners and images all cost you. A plain-text message with one link to a real domain reads like mail from a person. A message with a tracking pixel, a bit.ly link and a footer image reads like a newsletter, and newsletters go to Promotions.

Volume shape. Sending 30 messages spread across a working day looks human. Sending 30 in ninety seconds does not. Randomised intervals matter more than most senders expect.

List quality. Bounces above 3 percent tell the receiving network you bought a list. Verify every address before it enters a sequence, and drop catch-all domains into a separate lower-volume segment rather than mixing them in.

Open tracking now costs more than it returns

Apple Mail Privacy Protection has been prefetching images since 2021, which inflates open rates for anyone reading on an iPhone. Gmail proxies images through its own cache. The number your tool reports as an open rate is a blend of real humans and machines, and you cannot separate them.

Meanwhile the pixel itself is a deliverability cost: it is a remote image load from a tracking domain, which is exactly the pattern filters use to identify bulk mail. Under the ePrivacy Directive it also counts as storing or accessing information on a subscriber's device, which in several member states requires consent you do not have from a cold contact.

Turn it off. Measure reply rate and meeting rate, which are the two numbers that survive scrutiny anyway.

Diagnosing a campaign that has already gone quiet

Reply rate falls off a cliff and nobody changed the copy. Work through this order.

Buying a new domain is the reflex answer and it is usually wrong. A domain with a damaged reputation recovers over six to eight weeks of reduced volume. A new domain starts the three-week warm-up again and inherits none of the history you already paid for.

What this costs

Three domains at about 12 euros a year each, nine mailboxes on Google Workspace at 6.80 euros a month, a sending platform between 40 and 100 euros a month, and verification at roughly 0.004 euros per address. That is somewhere near 120 euros a month for infrastructure capable of about 5,000 first touches.

The three weeks of warm-up cost more than all of it. That is the line most budgets leave out.