Email deliverability

Sending a message is easy. Establishing who sent it, preserving trust and working out why a receiver rejected it are separate problems.

These guides cover the parts that can be verified: authentication, provider requirements, reputation signals and the exact responses returned during delivery. Provider policies change, so each guide carries a review date and links to the primary material used.

Blue Canoe operating recommendations are labelled as such. They are not presented as provider requirements.