A brand-new sending domain has no reputation with mailbox providers, good or bad. Sending at full volume on day one reads as spam-like behavior, regardless of content quality, and can suppress inbox placement for months.
Start with SPF, DKIM, and DMARC published and passing before the first message goes out. Mailbox providers use these records to decide whether a domain is worth evaluating at all; skipping them delays every later step.
Ramp volume gradually, doubling roughly every few days rather than jumping straight to steady-state traffic. Send to your most engaged recipients first: accounts that open, click, and reply give mailbox providers a positive signal early, before less-engaged sends are introduced.
Watch bounce and complaint rates throughout the ramp. A hard-bounce rate above roughly 2% or a complaint rate above 0.1% is a signal to pause the ramp and clean the list rather than push through it.
Isolate the new domain's reputation from any existing sending identity while it warms up. PulsePigeon keeps transactional and marketing traffic on separate lanes and IP pools for exactly this reason: one bad marketing send should never delay a password reset.