Why do my cold emails go to spam?
Short answer
Almost always authentication or reputation, not wording. Check SPF, DKIM, and DMARC are all passing on the exact sending domain, then check volume and complaint rate. Spam-word checkers are largely folklore. Modern filters weight sender reputation far more heavily than vocabulary.
Check these in order
1. Authentication, on the exact sending domain. SPF, DKIM, and DMARC all passing. Not “set up” but passing, verified by sending to a seed address and reading the headers. This is the single most common cause and the most frequently assumed-fine.
2. The sending domain itself. If you are sending cold volume from your primary domain, you are risking the domain your invoices and contracts go through. Most teams that do this once do not do it twice. A separate domain contains the blast radius.
3. Volume and ramp. A domain with no sending history that suddenly sends hundreds of messages looks exactly like a compromised account, because that is what compromised accounts do.
4. Complaint and bounce rate. Bounces from scraped lists damage reputation quickly. This is where list quality turns into a deliverability problem rather than a targeting one.
5. Then, and only then, the content.
On spam-word checkers
The idea that avoiding words like “free” or “guarantee” meaningfully changes placement is mostly folklore at this point. Reputation-based filtering dominates. A message from a well-authenticated domain with good engagement history will land while containing every word on those lists; a message from a cold domain with failing DKIM will not land no matter how carefully it is phrased.
This is worth saying plainly because “run it through a spam checker” is the most common advice on this query, and it is the least likely to help.
What actually changes outcomes
- Authentication passing, verified in headers rather than assumed.
- A dedicated sending domain, warmed gradually.
- A list where the addresses exist.
- Volume proportionate to your history.
- Genuine reply rates, because engagement feeds reputation.
That last point is the uncomfortable one: deliverability and message quality are not independent. Filters watch whether people reply, archive, or delete. A campaign that nobody wants degrades its own delivery over time, which is a reasonable thing for a filter to do.
What this is based on
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Deliverability is the single most common cold-email theme in practitioner discussion, ahead of copy, targeting, and tooling.
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'Cold email spam folder fix' is among the weakest SERPs we sampled. Forum threads rank above vendor content, indicating no authoritative published answer.
Our analysis of 97 SERPs, August 2026
What we don't know
- · We have not run our own deliverability testing. This page reflects what practitioners report and what the authentication standards actually require, not measurements we made.
- · Filter behaviour differs between Google, Microsoft, and everyone else, and none of them publish their weighting. Anyone claiming to know the algorithm is guessing.
On the search results for this question: Weak SERP. Forums rank, no vendor owns it.
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