The short answer
Emails land in spam for three main reasons: your domain is not authenticated (SPF, DKIM and DMARC), your list is not clean (old, bought or non-consented addresses) and people mark your emails as spam. Since 2024 Gmail and Yahoo, and since 2025 Outlook, require bulk senders to have full authentication and one-click unsubscribe. Here is what to do, step by step.
What Gmail, Yahoo and Outlook require
Since February 2024, Google and Yahoo have enforced rules for anyone who sends large volumes of email to their users. Microsoft did the same for Outlook.com and Hotmail from May 2025. In short:
- All senders: at least SPF or DKIM, and spam complaints below 0.3% (Google recommends staying below 0.1%).
- Anyone sending more than 5,000 emails a day to Gmail or Outlook: SPF and DKIM, plus a DMARC policy (even just “p=none”) aligned with the sender’s domain.
- Marketing emails: one-click unsubscribe (the RFC 8058 standard), with unsubscribe requests honoured within two days.
- Outlook: since 5 May 2025 it rejects email from senders above 5,000 a day that are not authenticated.
Even if you send fewer than 5,000 emails a day today, it pays to follow the same rules: filters reward senders who do.
SPF, DKIM and DMARC in plain English
- SPF is a list, published in your domain’s DNS, of the servers allowed to send email for you.
- DKIM is a digital signature on every email: it proves the message really came from you and was not changed on the way.
- DMARC tells Gmail and the others what to do with an email that uses your domain but fails the checks, and sends you reports.
You turn them on by adding a few DNS records wherever you bought your domain. On Spedito it is four records to copy, with instructions for GoDaddy, Namecheap, IONOS, OVH, Cloudflare and the rest: see Verifying your domain.
Your list matters more than your subject line
Filters mostly look at how people react. A healthy list has few bounces, few complaints and plenty of opens. To keep it that way:
- Only email people who signed up, and recently. Never use bought lists: they are full of abandoned addresses, some of them spam traps set on purpose.
- Use double opt-in: it blocks typos and fake sign-ups.
- Remove people who have not opened anything in many months, after one last email asking whether they want to stay.
- Make unsubscribing easy: people who cannot find the link press “spam”, which is far worse.
- Write regularly: a list that hears from you after a year of silence reacts badly.
Content and habits that help
- Always use the same, recognisable sender name: your business name.
- Write real text, not a single image: filters cannot read images, and many people do not load them.
- Use clear, honest subject lines, without shouting capitals or exaggerated promises.
- Keep links few, pointing to your own site, and avoid link shorteners.
- Send yourself a test before every send.
- With a new domain, start slowly: a few hundred emails a day, then more.
What Spedito does for you
Part of the work is done by the platform. On Spedito:
- every email has one-click unsubscribe, including the RFC 8058 technical header, in the recipient’s language;
- addresses that bounce permanently are stopped, and temporary problems are retried;
- anyone who marks an email as spam is unsubscribed automatically;
- if bounces or complaints go over the safety thresholds, sending pauses and we contact you to fix it together;
- new accounts ramp up gradually during their first 14 days, to protect the domain’s reputation;
- clicks made by corporate security scanners are not counted, so your reports stay accurate.
All the details are in Bounces, spam and delivery.
Frequently asked questions
Why do my newsletters land in Gmail’s Promotions tab?
Promotions is not spam: Gmail puts commercial emails there, even perfect ones. Your readers find you there. There is no trick to reach the Primary tab: write useful emails and ask subscribers to move you.
Do I need DMARC if I send few emails?
It is not required by law, and the strictest rules apply above 5,000 emails a day. But with SPF, DKIM and DMARC your emails are more credible to every provider, and nobody else can send in your domain’s name.
How many spam complaints are too many?
Google asks senders to stay below 0.3% and recommends below 0.1%: at most one complaint per thousand emails.
Can I use Spedito with a Gmail address?
Not for newsletters: Gmail, Outlook and Yahoo do not authorise other platforms to send on their behalf, and your emails risk being rejected. You need an address on your own domain, which you can verify in a few minutes.