What is cold email deliverability?
It's the share of your emails that land in the inbox, rather than spam, promotions or nowhere at all. Inbox providers decide that using who you are (authentication), what you've done before (reputation) and how people respond (opens, replies, complaints).
You can't see it directly in most sending tools. A high open rate from a list that never replies, or a sudden drop in replies, is often the first sign something's wrong.
What do SPF, DKIM and DMARC actually do?
They're DNS records that prove your email is really from you. Each one does a different job.
- SPF lists the servers allowed to send email for your domain.
- DKIM adds a signature to each email, so the receiver can check it wasn't changed and really came from your domain.
- DMARC tells receivers what to do when SPF or DKIM fail, and sends you reports. It also checks the From address lines up with the domain that passed.
What do Google, Yahoo and Microsoft require?
Google's email sender guidelines ask every sender to set up SPF or DKIM, use valid DNS and secure connections, and keep spam complaint rates low, which you can watch in Google Postmaster Tools. Bulk senders, which Google defines as around 5,000 or more messages a day to personal Gmail accounts, must set up SPF, DKIM and DMARC, align the From domain, and offer one-click unsubscribe on marketing email.
Yahoo publishes similar requirements, and Microsoft now asks high-volume senders to Outlook.com addresses to pass SPF, DKIM and DMARC. Cold outreach rarely hits those volumes, but treat the bulk rules as the standard anyway. They're what a trustworthy sender looks like.
How do you set up cold email deliverability from scratch?
Follow these eight steps in order. Skipping the early ones is what lands campaigns in spam.
- Buy a separate sending domain that's clearly yours (a close variant of your main one), so a bad week never touches your main email.
- Set up SPF, DKIM and DMARC on it, starting DMARC at p=none so you can read the reports before tightening it.
- Point the sending domain's website at your real site, so anyone who checks finds a real business.
- Create a small number of real inboxes with real names, photos and signatures.
- Warm each inbox up gradually: low volumes at first, rising slowly, with real conversations.
- Verify every address before you send. Bounces damage reputation quickly.
- Keep daily sends per inbox modest, and spread them through the working day.
- Watch replies, bounces and complaints every day. If any move the wrong way, stop and fix it before sending more.
What in the email itself hurts deliverability?
Less than people think, but some things matter. Heavy images, lots of links, tracking pixels and link shorteners all look like marketing mail. Plain text with one link at most, or none in the first email, reads like a person writing to a person.
The biggest factor is relevance. If people mark you as spam, inbox providers learn fast. If they reply, that helps. The best deliverability work happens before you send: a tight list of people your offer actually helps.
How do you know if you're landing in spam?
Check Google Postmaster Tools for your sending domain's reputation and spam rate, read your DMARC reports, and send test emails to accounts you control on Gmail and Outlook. A sudden fall in replies with no change in the list is a warning sign. Pause, check, then restart slowly.