Staying High Is a Discipline

This is my favorite curve of the three, and it's the least exciting to look at: four months, flat, High. Nothing happened. That's exactly the point — this is what a healthy email program looks like from the outside, and it's worth writing down what "nothing" is made of.

What the flat line is made of

No heroic saves, no clever tricks. A short list of unglamorous habits, held without exception:

• Consistent volume. No day-over-day jumps beyond ~30%. Big sends are planned as ramps, not cliffs.
• Engaged-first sending. Campaigns prioritize 30/60/90-day engagement tiers. The full list is not a campaign audience; it's a liability that occasionally gets mailed in careful slices.
• Every new flow is audited before launch. Link count, personalization depth, authentication — checked before the first send, not after the first dip.
• Weekly Postmaster review. Domain reputation, spam rate, one look every week. Ten minutes. The point isn't to react — it's to never be surprised.
• Monthly list hygiene. Subscribers with 90+ days of silence get sunset. Not "suppressed someday." Removed from regular sending, on a schedule, every month.

What boring buys you

At High, this sender's Gmail open rate holds in the 35–50% band. That number is the entire business case: email revenue you can plan around, launches you can trust, and a channel that doesn't need rescuing. The comparison I give clients: a domain at High with a modest list often out-earns a domain at Medium with triple the list — because the emails actually arrive.

The real lesson

You don't stay at High by doing something brilliant once. You stay by refusing the dumb things: no sudden volume spikes, no cold-segment blasts, no "just this once" full-list sends because a target is due. Every flat month on this curve is a dozen small refusals.

High is not a finish line. It's an operating state — and the moment you treat it as done, you're one enthusiastic campaign away from this curve instead.

If you're still climbing rather than maintaining, the level-by-level playbook is in the domain reputation guide.