Troubleshooting
Why your transactional email goes to spam
Transactional mail lands in spam for reasons in a specific order of likelihood: failing authentication (SPF, DKIM, DMARC), a new or damaged sending reputation, sending marketing content from a transactional domain, or low engagement. Check authentication first — it's binary, it's the most common cause, and it's the only one you can fix in an afternoon.
Why your transactional email goes to spam
A diagnostic order of operations for transactional mail landing in spam: authentication, reputation, content, and the engagement signals you can't see.
Spam placement is not one problem. It is a score assembled from many signals, and the useful approach is to eliminate them in order of how often they're the actual cause and how cheaply you can rule them out.
1. Verify authentication actually passes
This is the most common cause and the easiest to confirm. Send a message to an address you control, open the raw source, and read the Authentication-Results header. You want dkim=pass, spf=pass, and dmarc=pass. Anything else, fix that before looking at content.
Gmail and Yahoo bulk sender rules
Since 2024, senders above roughly 5,000 messages a day to Gmail or Yahoo must have SPF, DKIM, and DMARC, one-click unsubscribe on marketing mail, and a spam complaint rate under 0.3%. Below those thresholds the same signals still apply, just less strictly.
2. Consider your sending reputation
Reputation attaches to your domain and sending IP, and it is built from history you may not have yet. A brand-new domain has no reputation, which is not neutral — it is treated with suspicion. Ramp volume gradually rather than sending your entire list on day one.
Reputation damage is usually self-inflicted and specific: sending to addresses that hard-bounce, mailing people who never opted in, or ignoring complaints. Automatic suppression of bounced and complaining addresses is the single most effective protection, which is why it should not be something you can switch off.
3. Don't send marketing from your transactional domain
This is the mistake that quietly destroys password-reset delivery. Marketing mail attracts complaints; complaints damage the reputation of the domain that sent them. If that is the same domain as your transactional mail, your password resets inherit the damage.
- Use a subdomain for marketing (e.g. news.yourdomain.com) and another for transactional
- Never put a marketing footer or promotional content in a transactional message
- Keep one-to-many sends off your transactional sending path entirely
4. Then look at content
Content matters less than most people assume, and chasing spam-word lists is mostly wasted effort. The content issues that do matter are structural: a large image with almost no text, link shorteners, mismatched display and actual link targets, or a missing plain-text alternative.
5. Engagement you can't measure
Mailbox providers weight whether recipients open, reply, and move messages out of spam. You can't see these signals directly, which makes them the hardest to act on. The practical lever is list hygiene: stop mailing addresses that never engage, because continuing to send to them actively lowers your score.
Frequently asked questions
Does a dedicated IP improve deliverability?
Only above meaningful, consistent volume. A dedicated IP means your reputation is entirely your own — which cuts both ways. At low volume you can't generate enough consistent traffic to build a good reputation, so a well-managed shared pool usually performs better. Dedicated IPs start making sense in the high tens of thousands per month and up.
How do I check if my domain is blacklisted?
Query the major DNSBLs (Spamhaus, Barracuda, SORBS) for your sending domain and IP. A listing usually points at a specific incident — a compromised account, an imported list, or a spike in complaints — and delisting requires fixing that cause first. Delisting without fixing the cause gets you relisted.
Should transactional email have an unsubscribe link?
No, and adding one can hurt. Genuinely transactional mail (password resets, receipts, security alerts) is expected by the recipient and exempt from unsubscribe requirements. Adding a marketing footer to it blurs the line, and if recipients unsubscribe from transactional mail they stop receiving messages they actually need.