The practice of sending an email to each individual recipient at the specific time of day they're statistically most likely to engage, rather than sending an entire list at one fixed time, often automated by a platform analyzing each recipient's past open behavior.
Why it matters
Recipients don't all check email at the same time, and a send that goes out at a poor time for a given individual can go unopened even if the content and subject line are strong — send time optimization aims to remove timing as a limiting factor for engagement.
In a sentence
"Once we turned on send time optimization, the same email got a noticeably higher open rate than our previous fixed 9am send."
Related terms
- Often confused with: Dayparting (Category 7, Part One) — send time optimization typically personalizes timing per individual recipient for email specifically; dayparting more commonly refers to scheduling ads to run during specific hours across an entire audience, not personalized per individual).