Cold email deliverability for service firms: a plain-English checklist
Most cold email fails before anyone reads it, because it lands in spam. Here is the setup we use, in plain language.
1. Never send from your main domain
Use separate domains that resemble your brand. If something goes wrong, your everyday email keeps working.
2. Authenticate every domain
Set up SPF, DKIM and DMARC. Google and Yahoo have required authentication from bulk senders since 2024, and Microsoft added similar rules for Outlook in 2025. See Google's sender guidelines.
3. Warm up new inboxes
New inboxes need 2 to 3 weeks of gradually increasing, normal-looking email before they send outreach.
4. Keep volume modest
Around 25 to 30 emails per inbox per day. Need more volume? Add inboxes rather than pushing each one harder.
5. Verify every list
Keep bounces under 2%. Remove invalid addresses, and send to “catch-all” addresses separately in small batches.
6. Write like a person
Plain text, no images, no links in the first email, an honest subject line.
7. Follow the law
In the US, CAN-SPAM requires a clear sender, a postal address and a working opt-out honoured within 10 business days. The FTC's guide is short and worth reading.