High-volume sending held steady while Gmail placement recovered

RunwaySale.co.za operates high-frequency promotional email at enormous scale—on the order of 20 million or more messages per day, with sends often exceeding once per day during peak periods. At that volume, even small reputation leaks show up fast in Gmail placement.

In May 2017, seed-based Gmail inbox placement had slipped to about 64%. The root issue was list quality: years of acquisition and reactivation had left a large share of the file unengaged or risky relative to Gmail’s engagement signals.

We executed aggressive list cleaning—roughly 50% of the list removed or permanently suppressed from regular promotional mail—so remaining sends concentrated on recipients who could still engage. That reduced negative signals per send and gave Gmail a cleaner read on domain and IP reputation.

After the hygiene pass, Gmail inbox placement in testing recovered to about 95%. The takeaway for high-volume programs: at mega-scale, list hygiene isn’t a “nice to have”—it’s often the primary lever when authentication is already sound and volume can’t be turned down.