How do I stop marketing emails going to spam?
Authenticate the domain with SPF, DKIM, and DMARC; keep bounce rate under 5% and complaint rate under 0.1%; and honour unsubscribes immediately through a single suppression list. Anyone sending 5,000 or more messages a day to Gmail or Yahoo must also include RFC 8058 List-Unsubscribe and List-Unsubscribe-Post headers. AeroCampaign adds those headers to every send and offers only DKIM-verified identities as From addresses.
- Gmail and Yahoo require RFC 8058 one-click unsubscribe for senders of 5,000+ messages per day.
- Complaint rate must stay below 0.3% under Gmail's bulk-sender rules; below 0.1% is the safe target.
- Only DKIM-verified identities are offered as From addresses.
- List-Unsubscribe and List-Unsubscribe-Post headers are added to every AeroCampaign send.
- The one-click unsubscribe endpoint writes directly to the suppression engine.
Most deliverability advice focuses on content — subject lines, spam words, image ratios. In practice the dominant factors are authentication, list hygiene, and complaint rate. A well-authenticated sender with a clean list can be blunt in their copy; a poorly authenticated sender cannot write their way out of it.
The failure mode we see most often is not a missing unsubscribe header but a complaint rate quietly climbing past 0.3% while nobody watches the number.