Email deliverability: why your mail lands in spam and what fixes it

Email deliverability is whether your mail reaches the inbox rather than the spam folder or nowhere at all. It is distinct from delivery: a message can be accepted by the receiving server — technically delivered — and still be filed where nobody will see it. That gap is where most business email quietly fails.

The good news is that the causes are boringly consistent. Authentication that was never set up, a domain with no sending history, lists containing addresses that no longer exist, and recipients who mark you as spam. Almost nothing about deliverability depends on subject-line wording, which is where most advice concentrates.

What actually determines whether you reach the inbox

• Authentication: SPF, DKIM and DMARC published correctly for your sending domain. Without these, major providers increasingly reject or quarantine bulk mail outright.
• Domain and IP reputation, built from how recipients have treated your mail over time. New domains have no reputation, which is neither good nor bad but requires warming up.
• Complaint rate — the proportion of recipients who hit "report spam". This is the single most damaging signal and the thresholds are low.
• Bounce rate, especially hard bounces to addresses that do not exist. Repeatedly mailing dead addresses is read as a sign you did not collect them properly.
• Engagement: opens, replies, and mail being moved out of spam. Providers weight recent positive interaction heavily.
• List hygiene: how the addresses were obtained and how recently they were active.
• Consistency of volume. A domain that sends thirty messages a day and then suddenly sends five thousand looks compromised.
• The technical basics: valid reverse DNS, a real reply-to address, and a working unsubscribe mechanism for bulk mail.

Never buy or scrape a list. Beyond the legal problems in most jurisdictions, purchased lists contain spam traps — addresses that exist only to catch senders who did not get permission. Hitting one can damage your domain's reputation in ways that take months to repair, and no amount of good practice afterwards undoes it quickly.

Getting it right

1. Publish SPF, DKIM and DMARC for your sending domain before you send anything at volume, and verify them with a checker rather than assuming.
2. Send from a real domain you control, with a monitored reply address. "noreply@" is legal but it removes the replies that improve reputation.
3. Warm up a new domain: start with small volumes to people who know you and expect your mail, and increase gradually over weeks.
4. Verify addresses at the point of collection and remove hard bounces immediately — not eventually.
5. Separate transactional mail from marketing mail, ideally on different subdomains, so a campaign problem cannot poison your invoices and password resets.
6. Make unsubscribing easy and instant. A person who cannot find the unsubscribe link reports you as spam, which costs far more.
7. Prune inactive recipients periodically. Mailing people who have ignored you for a year suppresses engagement metrics for everyone.
8. Read your DMARC aggregate reports — they show who is sending as your domain, including anyone spoofing it.

Transactional mail is not exempt

Invoices, password resets and order confirmations are the messages that most need to arrive, and they are frequently the least well configured — sent from an application, on a subdomain nobody checked, with authentication that was set up by whoever installed the software. Test them the way you would test a campaign: send to accounts on the major providers, check where they land, and check that the sending domain passes authentication. A password reset in the spam folder produces support tickets, not just annoyance.

Ettex Mail runs mail on your own domain, which is the foundation everything else sits on: per-address signatures so branding is consistent across mailboxes, reusable replies for messages you send repeatedly, scheduled send, snooze and follow-ups, and sixteen transactional layouts for the automated messages. Because the mail is on your domain rather than a shared consumer address, SPF, DKIM and DMARC are yours to publish and yours to benefit from. Bulk sends and campaign wording belong with the templates you keep in Ettex Docs, and the recipient records live in Ettex Contacts with tags for consent and activity.

Plainly: Ettex is not a deliverability tool. There is no inbox-placement testing, no seed lists, no reputation monitoring, no spam-score checking, no dedicated IP management and no automatic list verification. It hosts mail on your domain and shows you DMARC aggregate reports; the checks described above use free external tools or a dedicated deliverability service.

An address that reaches many people needs an owner more than a clever name. A distribution list should derive its membership from a team or a role rather than from individuals added by hand, because derived membership is the only kind that survives a reorganisation.

Why mail goes to spam

• SPF, DKIM or DMARC missing or misconfigured — still the most common single cause.
• Sending bulk mail from a domain with no history at full volume on day one.
• Hard bounces left in the list and mailed repeatedly.
• Purchased or scraped lists, with the spam traps they contain.
• No visible unsubscribe, converting would-be unsubscribers into complainants.
• Marketing and transactional mail sharing a domain, so a bad campaign takes the invoices down with it.
• Sudden volume spikes that look like a compromised account.
• Mailing people who have not engaged in a year, which drags engagement signals down across the board.

Two configurations do most of the work. Spf dkim dmarc are the domain records that authenticate your mail, and a data retention policy governs how long you keep the lists — an old list with high bounce rates damages deliverability more than most content mistakes.

Email deliverability is mostly configuration and hygiene: authenticate the domain, warm it up, remove bounces, make unsubscribing easy, and keep transactional mail away from campaigns.