Deliverability

Whether your emails land in the inbox at all. The silent multiplier on every other outbound metric.

Deliverability is decided before anyone reads a word: domain reputation, authentication (SPF, DKIM, DMARC), sending volume per mailbox, bounce rate, and how many people mark you as spam. A campaign at 2% reply rate on a burned domain might be a 6% campaign on a healthy one.

The habits that keep it healthy are unglamorous: warm new domains slowly, cap each mailbox at a few dozen sends a day, verify every address before sending, and stop a campaign the moment bounces climb.