Email deliverability
Deliverability measures the ability of messages to reach the inbox rather than spam. It depends on authentication, the reputation of the sending IP and domain, and the quality of the sending practices.
In practice
The SPF-DKIM-DMARC trifecta is the entry ticket; reputation does the rest — complaints, spam traps, consistent volumes. A new domain warms up progressively. Infrastructure matters too: coherent reverse DNS, clean IP, managed queues. The useful test is not whether the mail sent, but where it arrived.