Answers · Email delivery · As of 6 October 2026
Why do my emails end up in spam?
Short answerMost of the time, there is no proof that the email really comes from your domain. Gmail requires SPF or DKIM from all senders and, from 5,000 emails a day, DMARC1 in addition. Fully configured domains arrive in the inbox around 2.7 times as often3.
What Gmail requires
Since 1 February 2024, Gmail rules have applied to all senders2. Everyone must set up SPF or DKIM. Anyone sending more than 5,000 messages a day must set up SPF, DKIM and DMARC1.
For advertising and newsletters, one-click unsubscribe is added2.
What Outlook requires
Microsoft also requires domains sending more than 5,000 emails a day to have SPF, DKIM and DMARC. Since 5 May 2025, Outlook has sorted emails without these records into the Junk folder. Rejected emails carry the error code 550 5.7.5154.
What the records deliver
SmartReach has analysed deliverability. Domains with SPF, DKIM and an effective DMARC policy land in the inbox around 2.7 times as often3.
The same analysis shows how big the problem is: around 17% of cold emails never reach the inbox3.
What to check first
Three entries in your domain's DNS: SPF, DKIM and DMARC. If one is missing or incorrect, the best copy will not help.
More detail (in German): What Gmail, Yahoo and Outlook require from senders
Sources
- Google: Email sender guidelines, Frequently asked questions: support.google.com
- Google: Email sender guidelines: support.google.com
- SmartReach: State of cold email, 23 July 2026: smartreach.io
- Microsoft: Outlook requirements for high-volume senders: techcommunity.microsoft.com
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