Most founders and marketers who suspect their email is underperforming never actually confirm it. They ask the engineering team, get a vague "SPF looks fine" answer, and move on. Three months later they discover that the welcome sequence has been landing in Promotions and 40% of their cold outreach never reached an inbox at all. This audit is designed to be run by the person who cares most about the outcome — usually not the person who configured DNS.
Thirty minutes, a free browser tab, and a Google Doc. At the end you will have a one-page summary that tells you whether your deliverability is healthy, at risk, or broken — and which specific person on your team needs to fix what.
Before you start: what you need
Grab a laptop, make a fresh Google Doc titled "Email audit — [date]", and have the following handy: the domain you send marketing email from, the domain you send transactional email from (often the same, sometimes different), access to your ESP dashboard (Mailchimp, Brevo, Klaviyo, whatever you use), and a recent campaign subject line so you can pull its headers if needed. If those domains are different, audit both — the problems are rarely the same on each.
Check 1: Authentication (5 minutes)
Authentication is the foundation. If SPF, DKIM or DMARC are misconfigured, nothing else you do matters much. You don't need to understand what each record does — you only need to confirm all three exist and pass.
- Open Inbox Check in a new tab and send one email to the seed address.
- Wait 60 seconds for results.
- Look at the authentication panel — SPF, DKIM, DMARC should each show PASS.
In your Google Doc, paste the three results. If any of them says FAIL, NONE, or SOFTFAIL, that is a technical ticket for your engineer. Note it and move on. You are not here to fix things today — you are here to inventory them.
Check 2: Inbox placement (5 minutes)
Authentication passing doesn't mean your mail is reaching inboxes. Gmail might flag it as Promotions, Outlook might junk it, Mail.ru might block it entirely. The same free test above shows placement across 20+ providers — Gmail Primary vs Promotions, Outlook Inbox vs Junk, Yahoo, ProtonMail, and regional ones like Mail.ru and Yandex if your audience includes the CIS.
Record two numbers in your doc: percentage landed in Primary/Inbox, and percentage of total that landed anywhere (including spam/junk). If Primary is under 70%, your reputation or content needs work. If anywhere-delivery is under 85%, your authentication or sending IP is the problem.
Inbox Check runs the placement test across 20+ real seed mailboxes with full screenshots, SPF/DKIM/DMARC verdicts and spam engine scores. Free, no signup — or use the API to script the audit into a quarterly cron job.
Check 3: Postmaster Tools (5 minutes)
Google Postmaster Tools gives you reputation data straight from Gmail. If you haven't set it up, do it now — it takes two DNS records and verifies in an hour. For the audit, just note the four headline metrics: domain reputation (should be High or Medium), IP reputation, spam rate (must be under 0.3%), and authentication pass rates.
If you don't have Postmaster Tools set up, write that down as a finding. Half the founders who run this audit discover they've been flying blind for two years.
Check 4: List hygiene (5 minutes)
Open your ESP dashboard. You're looking for four numbers from your last three campaigns: bounce rate, unsubscribe rate, complaint rate, and the size of the "inactive" segment (opened nothing in 90 days).
- Bounce rate over 2% — list quality issue
- Complaint rate over 0.1% — content or consent issue
- Inactive segment over 30% — you are training filters to see you as irrelevant
Record the numbers in your doc. Don't solve anything — just write them down.
Check 5: Content sanity (5 minutes)
Open the most recent campaign in preview. Skim it looking for the four most common content smells: ratio of images to text (should not be majority images), number of links (should be under 10 for marketing, under 3 for transactional), subject line gimmicks (ALL CAPS, excessive punctuation, spam words), and from-name consistency (is it the same human or brand name you used last campaign?). None of these are automatic disqualifiers, but a campaign that hits three out of four is asking to be filtered.
Check 6: DNS record age (5 minutes)
SPF, DKIM and DMARC records drift over time. A vendor gets removed from SPF, a DKIM selector rotates, someone tightens DMARC from p=none to p=quarantine without telling marketing. The final check is simply: when were these records last reviewed? If the answer is "I don't know" or "over a year ago", that is your cue to schedule a formal review.
The one-page output
At the end of 30 minutes your doc should look something like this:
- Authentication: PASS / PASS / PASS — or a list of failures
- Inbox placement: X% primary, Y% anywhere
- Postmaster reputation: High / Medium / Low (or "not set up")
- List hygiene: bounce %, complaint %, inactive %
- Content smells: 0–4 warnings
- DNS last reviewed: date or "unknown"
Under each line, one sentence: is this healthy, at risk, or broken? That is the entire audit. Send it to whoever owns email infrastructure with a simple note: "Here is where I think we stand. What would you change?" You've just turned a vague anxiety into a specific conversation.