"It's going to spam" has a dozen possible causes. Check them in the wrong order and you'll spend a month rewriting subject lines for a problem that was never about content.
Every client who comes to us with "our emails are going to spam" has already tried the same first move: rewriting the email. New subject line, fewer exclamation points, a different template. None of it works, because content is rarely the actual cause, and checking it first means ruling out the cheap, obvious thing last instead of first.
Pull up your SPF, DKIM, and DMARC status before anything else. A domain failing any of these gets treated as suspicious by every major provider, regardless of what the email says. This step takes ten minutes and rules out the single most common cause we see. See our full breakdown of these three records if you haven't set them up correctly yet.
If you send enough volume to Gmail, Google Postmaster Tools shows your actual domain and IP reputation, straight from Google, not an estimate. Microsoft SNDS does the same for Outlook and Hotmail. A reputation marked "bad" or "low" explains filtering on its own, and no content change touches it. Reputation moves with sending history, not with next week's email.
Two metrics decide whether providers treat you as a legitimate sender: bounce rate and spam complaint rate. Gmail and Yahoo's bulk sender guidelines set a hard line at 0.3% complaints; cross it and filtering tightens fast. We aim for clients to stay under 0.1%, since volume spikes happen and that gives room before hitting the real limit.
A list that hasn't been cleaned in a year accumulates dead addresses, spam traps, and disengaged recipients who mark mail as spam out of habit rather than open it. Sending to that list drags reputation down with every send, and no authentication fix offsets it.
Once authentication, reputation, and list hygiene check out, content is worth a look: shortened links through unfamiliar domains trigger filters, image-heavy emails with little text read as low-effort to some filters, and a domain you link to that's itself blacklisted drags your message down with it. This is real, but it's the smallest lever of the four, which is why it belongs last.
Run this check now: send a test email to Mail-Tester and read the full breakdown, not just the score. It separates authentication issues from content issues, which tells you where to look first.
Authentication, then reputation, then list hygiene, then content. Each step is cheaper and faster to check than the one after it, and each one, if broken, makes every later step irrelevant until it's fixed. Checking in reverse order is why "going to spam" problems drag on for months instead of getting resolved in a week.
Authentication gaps. Before looking at anything else, confirm SPF, DKIM, and DMARC all pass and align. A domain with a broken SPF record gets filtered hard by every major provider, and no amount of content tweaking fixes that.
Gmail and Yahoo's published bulk sender guidelines set the threshold at 0.3% spam complaints. Above that, expect filtering to tighten. Staying under 0.1% is the safer target, since spikes happen and you want headroom before hitting the hard limit.
Only if the problem was content in the first place, and most deliverability problems aren't. If authentication, reputation, and list hygiene all check out and you're still filtered, content and link reputation are worth reviewing. Checking content first, before the other three, is the most common wasted week we see.
Tell us the symptom. We'll run the full diagnostic order and tell you exactly which step broke.
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