Google and Yahoo sender requirements

For everyone sending to their users: authenticate with SPF or DKIM, send from IPs with valid forward and reverse DNS, use TLS, follow the message-format standards, and keep the spam-complaint rate below 0.3% (Google recommends staying under 0.1%).

Bulk senders (for Google, anyone who has sent close to 5,000 or more messages in a day to personal Gmail accounts) must also publish SPF and DKIM and a DMARC record (p=none at minimum), align the From domain with SPF or DKIM, and offer one-click unsubscribe (RFC 8058) on marketing mail, honouring requests within two days. Microsoft introduced similar requirements for senders of more than 5,000 messages a day to Outlook.com addresses in 2025.