Short answer
Almost always because the domain’s email authentication is incomplete. Publish SPF, DKIM and DMARC records for your domain and delivery improves markedly — Gmail and Outlook now expect all three from anyone sending regularly.
Beyond authentication, the things that matter are consistency and content: send from a real address at your own domain rather than a Gmail one, avoid all-caps subject lines and link shorteners, and never buy a mailing list.
New domains also carry no sending reputation at all, which takes a few weeks of ordinary sending to build.
Learn more
- Why are my emails going to spam?The real reasons email lands in junk folders — authentication, content, reputation and recipient behaviour — and a checklist to fix each one.
- SPF, DKIM and DMARC explainedWhat SPF, DKIM and DMARC each do, how they work together, and the order to set them up so your email reaches inboxes.
- Getting email delivered to Gmail and OutlookWhat Gmail, Yahoo and Microsoft require from senders, which rules apply to a small business, and how to meet them on Traxio.
Step-by-step
- Set up SPF, DKIM and DMARCIntermediate · 30 min · 8 steps
- Diagnose email delivery problemsAdvanced · 40 min · 9 steps
All email deliverability questions · All questions and answers