Glossary
Deliverability
The discipline of reaching inboxes instead of spam folders.
Deliverability is sender reputation made measurable: authentication (SPF/DKIM/DMARC proving you are who you claim), IP and domain history, bounce and complaint rates, engagement, list hygiene, and gradual warmup for new senders.
Gmail's bulk-sender rules made the floor explicit: authenticate everything, keep spam complaints under 0.1%, offer one-click unsubscribe. The ceiling is ongoing: monitor per-domain health, suppress the dead addresses, and never share reputation pools with spammers.
In Calder: Calder deliverability guide
Related terms
Transactional email · Bounce · Complaint · Suppression list · Email reputation