For newsletter operators
Newsletter Deliverability: Get Your Issues Into Inboxes, Not Promotions or Spam
Your open rate is a deliverability number before it is a content number. Inboxes shows where each issue actually lands across providers, why, and what to fix before the next send.
Inbox placement
67%
··%
· ·
Authentication
checking 130+ blacklists
Sample data. Seed results are estimates, not guarantees.
Newsletter deliverability, defined
Newsletter deliverability is whether the issues you send reach subscriber inboxes instead of the spam folder or the Promotions tab. It is driven by authentication (SPF, DKIM, DMARC), sender reputation, list hygiene, and template structure. Inboxes tests a real issue against a seed panel of live mailboxes at Gmail, Outlook, Yahoo, iCloud, GMX, and Zoho, shows the placement per provider, and returns ranked fixes: the DMARC record to publish, the include to add, the engagement segmentation to try. It then monitors your domain, IPs, and DMARC reports between sends. Seed results are directional estimates, and nobody can guarantee the inbox; the point is to find the fixable causes before your open rate finds them for you.
Why it fits
Built for the way you send
Test the issue before the blast
Send the draft to the seed list first. If Outlook routes it to spam or Gmail tabs it, you know before your subscribers do, not after the open-rate dip.
Fix the compliance basics fast
Google and Yahoo bulk-sender rules require aligned authentication and one-click unsubscribe. Inboxes flags exactly which requirement your setup misses and how to close it.
Watch reputation between sends
Blacklist hits and DMARC failures build up quietly between issues. Monitoring alerts you the day something moves, so fixes happen before send day.
// Who this fits
Independent writers and media teams sending regular issues on Substack alternatives, Ghost, beehiiv, Mailchimp, or their own ESP, who live and die by open rates.