Check if your cold emails are going to spam by sending a test to your own Gmail or Outlook account, opening the raw headers, and looking for SPF, DKIM and DMARC passing. That single check, run today, catches the most common cause and takes about five minutes.
This page is the fast version: the checks a business owner can run right now, what each one tells you, and what it misses. For the full list of causes and how to fix each one, read why cold emails go to spam. For the wider picture of cold email deliverability, start with our cold email deliverability guide.
What are the fastest checks for cold email going to spam?
Five checks cover most of what you need: a header check, your reply and open numbers, a blocklist lookup, Google Postmaster Tools, and your warm-up results if you have them running. None takes more than a few minutes, and together they tell you more than any single score.
| Check | What it tells you | What it misses |
|---|---|---|
| Header check (Gmail or Outlook) | Whether SPF, DKIM and DMARC passed on one message, right now | Only one message, one moment. Says nothing about volume or complaints |
| Reply rate and open rate | A steep drop can mean mail stopped reaching the inbox | Open rate is unreliable on Apple Mail; neither tells you which folder mail landed in |
| Blocklist lookup (MxToolbox) | Whether your sending IP or domain is on a public blocklist | Many filters, including Gmail's, do not rely on public blocklists at all |
| Google Postmaster Tools | Gmail-specific spam rate and authentication compliance, at scale | Needs real Gmail volume to show data, and the newest version dropped its reputation score |
| Warm-up spam rate, if you run warm-up | A daily trend before you send a single cold email | Measures warm-up traffic, not your actual cold campaign |
Run the header check first, on every new sending domain, before anything else. It is free, takes a minute, and catches the single most common cause: broken authentication.
How do you read a cold email's headers in Gmail?
Open a test email in Gmail, click the three dots in the top right, and choose "Show original." Gmail displays the full raw headers, including the authentication results for that one message.
- Send a real test email to a Gmail address you own.
- Open it, click the three dots, and select "Show original."
- Find the line starting
Authentication-Results:. Look forspf=pass,dkim=passanddmarc=pass. - If any says
fail,softfailornone, that record is broken. Fix it before testing anything else.
Google documents the authentication fields it reports in its sender guidelines, which also cover what Gmail expects from senders beyond authentication.
How do you read a cold email's headers in Outlook?
Open the message in Outlook on the web or new Outlook, select "More actions," then View, then "View message details," to see the same kind of raw header block. In classic desktop Outlook, open the message and choose File, then Properties, where the headers appear in the Internet headers box. Microsoft's own guide to viewing internet message headers covers all three paths.
- Open the test message.
- On the web or new Outlook: click "More actions," then View, then "View message details." In classic desktop Outlook: click File, then Properties.
- Search the header text for
Authentication-Results, the same field Gmail shows. - A pass on
spf,dkimanddmarchere means Outlook's own servers verified your sending setup on this message.
A header check that passes in Gmail and fails in Outlook, or the reverse, usually means a DNS record works for one provider's lookup pattern but not the other. Check the actual DNS records next, not just the header result.
What numbers tell you cold email is going to spam?
A sudden drop in replies, with no drop in volume, is the clearest sign that something changed in how your mail is being delivered. Open rate can point the same way, but it carries a caveat worth knowing before you trust it.
Apple's Mail Privacy Protection preloads remote images for Mail app users, which marks a message "opened" whether or not anyone read it. Mailchimp's explanation of Apple MPP walks through why this inflates open rates industry-wide, not just for cold email. A rising or flat open rate next to a falling reply rate can mean recipients are not engaging even though opens look fine.
Bounce rate and spam complaint rate are the two numbers that move first, before replies fall. Our cold email deliverability guide lists the healthy range and the point to act on each one, so this page will not repeat that table.
How do you check a cold email domain against blocklists?
Run your sending domain and IP through MxToolbox's blocklist check, which tests against more than 100 DNS-based blocklists and reports which ones, if any, list you.
A listing on a major blocklist is a real problem and usually explains mail bouncing or filtering hard at providers that consult that list. But a clean blocklist result does not mean your mail is reaching the inbox. Gmail, Outlook and Yahoo mostly run their own reputation systems rather than leaning on public blocklists, so passing this check is a good sign, not a clearance.
Does Google Postmaster Tools tell you if cold email is going to spam?
Google Postmaster Tools reports a Gmail-specific spam rate and your authentication compliance status, for domains sending enough volume to Gmail accounts to generate data. It is free to set up and worth having running before you need it.
Two limits matter for cold email specifically. A new or low-volume domain can show a blank dashboard for weeks, since Google suppresses data below a volume floor for privacy. A blank chart is an absence of data, not a clean result.
The bigger change is version two of Postmaster Tools. It has dropped the Domain and IP Reputation dashboards entirely, replacing them with compliance and spam rate views only. See Google's own notice on the change before trusting an older guide that still talks about a reputation score. That dashboard no longer exists in the current version.
Our email deliverability test guide covers Postmaster Tools setup and seed list placement tests in full, including how to calculate an inbox placement rate. This page stops at the check itself.
How does Pipefire check cold email for spam automatically?
Pipefire reads a warm-up spam rate from every mailbox it runs, on a loop that checks again every 6 hours. A mailbox is held out of cold sending until its warm-up mail stays under a 10% spam rate across at least 20 warm-up emails, measured over the trailing 7 days.
That gives a mailbox a continuous version of the header check above, running against real warm-up traffic before a single cold email goes out. It measures warm-up mail rather than the cold campaign itself, so it is not a substitute for checking your own sending domain's headers and numbers.
It does catch a sliding mailbox early, rather than after a client notices replies have stopped. Our deliverability page shows the other thresholds Pipefire enforces the same way, for bounces and spam complaints.
Check if my cold emails are going to spam FAQ
How do I know if my cold emails are going to spam without a paid tool?
Send a test email to a Gmail or Outlook account you own and read the headers. If SPF, DKIM and DMARC all pass and your reply rate has not dropped, you likely are not in spam. A paid placement tool gives a wider view, but the header check costs nothing and takes a minute.
Why are my cold emails going to junk but not everyone's?
Providers score each recipient and each sending domain separately, so a message can land in the inbox at one provider and junk at another. Check headers and complaint patterns by provider rather than assuming one result applies everywhere; our why cold emails go to spam page covers the six causes behind this.
Does a clean blocklist check mean my cold email is not going to spam?
No. A blocklist listing is a real red flag, but passing a blocklist check does not mean your mail reaches the inbox. Gmail, Outlook and Yahoo mostly filter on their own reputation signals rather than public blocklists.
Can I trust my open rate to tell if cold email is going to spam?
Not on its own. Apple Mail Privacy Protection marks many messages "opened" automatically, which inflates open rate regardless of where the message landed. Watch reply rate alongside it, and treat a falling reply rate with steady volume as the stronger signal.
How often should I check if my cold emails are going to spam?
Check headers on every new sending domain before it starts cold sending, then again after any DNS change, volume increase or new list. Our email deliverability test guide has a fuller testing schedule for domains already sending.