If your emails are landing in spam folders instead of the inbox, it's almost always one (or several) of a handful of well-known causes. Here are the seven most common — roughly in order of how often they're the culprit.
This is the single biggest cause. Mail providers use these three records to verify a sender is legitimate; without them (or with a broken configuration), your email looks unauthenticated — a major spam signal. Run our Domain Health Score tool for an instant pass/fail check across all three, plus A, NS, and other supporting records.
Mail providers track the reputation of your sending IP and domain based on historical behavior — bounce rates, spam complaints, and engagement. A new domain or IP with no sending history, or one that's previously sent spammy content, starts with a reputation deficit that takes time (and clean sending practices) to build up.
As covered in our PTR record guide, mail servers check that your sending IP resolves back to a matching hostname. A missing or mismatched PTR record is a common, often-overlooked deliverability blocker — especially for self-hosted mail servers.
Excessive exclamation marks, ALL CAPS subject lines, spam-trigger words ("free," "act now," "guarantee"), broken HTML, or a poor text-to-image ratio can all raise a message's spam score, even when authentication is perfect.
High bounce rates and spam-trap hits (fake addresses planted specifically to catch senders using purchased or scraped lists) are one of the fastest ways to tank a sending domain's reputation, sometimes within a single campaign.
If your sending IP (or a shared IP if you use a provider) has been blacklisted by a service like Spamhaus, most receiving servers will reject or spam-folder anything from it, regardless of your own configuration. This is worth checking whenever deliverability suddenly drops.
Even with SPF and DKIM individually passing, a misaligned DMARC setup (covered in our DMARC guide) can still cause deliverability problems, since many providers weight DMARC pass/fail heavily in their filtering decisions.