Is deliverability luck or logic?

It's Logic. Deliverability follows predictable patterns based on authentication, reputation, engagement, and sending practices. Understanding these factors enables systematic improvement.

Randomness exists in individual message outcomes due to complex filter interactions. But aggregate patterns are predictable. Good practices reliably produce better results than poor practices.

When deliverability seems random, it usually means variables are not fully understood. Investigation typically reveals logical causes: authentication issues, reputation problems, engagement decline, or sending practice changes.