What Google publishes
From 1 Feb 2024 Google asks every sender to personal Gmail accounts to use SPF or DKIM and to keep the Postmaster spam rate below 0.30%, and advises staying under 0.10%. Senders of about 5,000 messages a day or more (Google words the threshold both ways) also need SPF and DKIM, DMARC, alignment and one-click unsubscribe.
A monthly checklist per source
List every tool that sends mail as your domain: the CRM, the newsletter tool, the billing system, the help desk. For each, have a test message sent to a mailbox you control and read the headers for SPF, DKIM and alignment. Read your DMARC reports for senders you do not recognise and note when each first appeared.
Compare the spam rate shown in Postmaster Tools with the 0.10% target and the 0.30% limit.
- One test message per source.
- A first-seen date for each unknown sender.
- The unsubscribe header on bulk mail.
What this does not do
Passing these checks does not guarantee inbox placement. They show your sending is set up as Google asks, and they catch drift after a new tool is added. This guide is authored advice built on the source above.
Sources and limits
- Google: email sender guidelines Checked 2026-10-12.
- From 1 Feb 2024 every sender to personal Gmail accounts needs SPF or DKIM and a spam rate below 0.30%; Google advises staying under 0.10%.
- Bulk senders (Google words the threshold both as 5,000 or more and as more than 5,000 messages a day) also need SPF and DKIM, DMARC, alignment and one-click unsubscribe.