Why your emails land in Promotions — and the fixes that actually move them

When open rates fall, the first instinct is to rewrite subject lines. That is the last thing worth changing. Inbox placement is decided mostly before the mailbox provider ever looks at your copy — by authentication, by your sending history, and by how the last few sends were received.

Fix authentication first

• SPF, DKIM and DMARC all published and aligned. Bulk senders are now expected to have all three; without them you are filtered before content is considered.
• DMARC starting at p=none so you can read reports, then tightened to quarantine once the reports are clean.
• A dedicated sending subdomain — mail.yourbrand.com — so marketing volume never damages the reputation of the domain your invoices go out from.
• One-click unsubscribe in the header, not just a link in the footer. It is now expected of bulk senders and it measurably reduces spam complaints.

Then fix the list

A list that has not been cleaned in a year is the single most common cause of a sudden placement drop. Suppress anyone who has not opened in six months, remove role addresses, and never re-import an old list to 'boost' a campaign. Complaint rate is the metric providers weigh hardest, and dead addresses raise it fast.

Then fix the sending pattern

• Warm new domains and IPs over two to three weeks. Volume from a cold domain looks exactly like a spam run.
• Send at a consistent cadence. Silence for two months followed by a full-list blast is a red flag.
• Segment by engagement and send your most engaged segment first. Early positive signal helps the rest of the send.
• Keep transactional and marketing streams on separate subdomains so a bad campaign cannot delay password resets.

Only then look at content

Once the plumbing is right, content signals matter at the margin: a readable text-to-image ratio, links pointing to the same domain you send from, no link shorteners, and a plain-text alternative that is genuinely readable. Promotions-tab placement is not automatically bad either — for offers it is where buyers look. It is only a problem when transactional and expected mail lands there.

Work in that order — authentication, list, pattern, content — and most inbox problems resolve inside one sending cycle.