Email deliverability: why your emails end up in spam

You polished the subject line, reread the text three times, picked the right day to send. And the open rate stalls, with no explanation. Often the problem is not in the message: it lies in what the recipient’s mailbox provider decided before even displaying it. This article from our digital marketing section explains why an email ends up in spam, and what a company of 20 to 500 people gains by settling the question once and for all.

Why does a legitimate email end up in spam?

Because on the internet, anyone can write an email pretending to be anyone. Mailbox providers have therefore learned to be suspicious by default. A message that does not prove its origin looks to them like an impersonation attempt; a message that many recipients report looks like spam, whoever the sender is.

This sorting does not only affect newsletters. Quotes, invoices, reminders, invitations: everything sent from your domain benefits or suffers from the same reputation.

SPF, DKIM, DMARC: three proofs, one goal

These three acronyms describe records placed in the configuration of your domain name. They change nothing in your emails, and everything in the trust given to them.

The benefit lies in the third point. DMARC links the address the recipient sees to the technical proofs, and tells mailbox providers what to do with a message that fails: let it through while warning you, quarantine it, or reject it. It also sends you reports, which often reveal forgotten services sending in your name: an invoicing tool, a form on the website, a support application.

What Gmail and Yahoo have required since 2024

In February 2024, Gmail and Yahoo turned these good practices into rules. They apply to all senders in their basic version, and in full to those who send a lot: at Gmail, the threshold is around 5,000 messages a day to Gmail addresses.

For marketing messages, both providers also require one-click unsubscribe, declared in the message header, and a visible unsubscribe link in the body. The minimum DMARC level required is the one that only monitors: the rule does not force you to reject failing messages, but it does force you to publish the policy.

The second half: recipients who want your emails

Authentication proves that the message comes from you. It does not prove anyone is expecting it. Complaints, dead addresses and recipients who never open anything damage your sender reputation, campaign after campaign.

1. 01A clean list.

   Addresses obtained with clear consent, and invalid addresses removed: our guide to cleaning CRM data applies to them first.

2. 02Expected sends.

   Segment by what each person asked for, rather than sending everything to everyone.

3. 03An easy exit.

   A one-click unsubscribe costs a contact; a spam complaint costs reputation for the whole list.

4. 04Continuous monitoring.

   DMARC reports and Google’s Postmaster Tools dashboard tell you what mailbox providers think of you.

What you gain from it

Sorted deliverability means campaigns that really reach their audience, quotes and invoices that arrive, and, with a DMARC policy that rejects failing messages, a domain that is much harder to spoof to trap your customers. It also means reliable measurement: when emails arrive, a low open rate finally speaks about the message, and no longer about the plumbing.

That is the starting point of our email marketing and CRM offer: set up the domain, connect sending to the CRM, then build the campaigns, within the broader framework of our digital marketing offer. For what comes next, our guide on how to run an email campaign lays the foundations of the message itself, and our article on marketing automation shows what can be handed to automated scenarios.

Frequently asked questions

Sources

1. Yahoo, Sender Best Practices (new tab)senders.yahooinc.com