A buried cannabis dispensary email domain was pulling a 0.55% open rate on a 64,171-send broadcast. A structured 5-phase warmup sequence rebuilt sender reputation in 25 days — lifting the full-list open rate to a sustained 18%+ and cutting wasted credits by 97%.
A recreational cannabis dispensary was bleeding out on email. Six months earlier, the program had been healthy — 25% open rates across 2,000-send weekly campaigns. Then the trajectory went one direction: 20% in September, 15% in November, 10% in December, 2.23% by early January. By February 1, a single 64,171-send broadcast pulled a 0.55% open rate — effectively a buried domain. The welcome email was running at 0.31%. The inbox providers had stopped trusting the sending reputation, and every additional broadcast was making it worse. The question wasn't "how do we send more" — it was "how do we climb back from a domain that's been effectively blacklisted by Gmail and Apple Mail without wiping the list and starting over." We built a structured 5-phase warmup playbook to rehabilitate the sender reputation from the inside out.
Results at a Glance (Domain Warmup Playbook)
Pre-Warmup Open Rate
0.55%
On a 64,171-send blast (Feb 1)
Post-Warmup Open Rate
18.17%
On the first full broadcast (Apr 3)
Open Rate Lift
3,203%
From baseline to steady state
Warmup Duration
25 Days
Jan 30 → Feb 27 first branded send
Peak Warmup Open Rate
49.45%
Phase 3 engaged micro-segment
Sends Eliminated
97%
64,171 → 1,921 for the same opens
All figures pulled directly from the dispensary marketing platform's attributed reporting, covering the pre-warmup broadcast baseline, the full 5-phase warmup sequence, and the post-warmup campaign calendar.
The Open Rate Trajectory — Pre-Warmup, Warmup, Post-Warmup
Pre-Warmup Broadcast · Feb 1
0.55% Open · 64,171 Sends
Warmup Phase 1 · Jan 30
41.67% Open · 96 Sends
Warmup Phase 3 · Feb 13
49.45% Open · 273 Sends
Post-Warmup Broadcast · Mar 19
19.12% Open · 1,914 Sends
The shape of a successful domain warmup is counterintuitive. Phase 1 and Phase 3 produce the highest open rates because the sends go to the smallest, most engaged micro-segments — the customers inbox providers already trust. As the list expands in later phases, the open rate settles toward the natural cannabis industry baseline of 17-19%. The Mar 19 broadcast is the real success metric: a full-list send holding steady at 19.12% — 33x the pre-warmup baseline of 0.55%.
The 5-Phase Warmup Playbook
Phase 1 · Diagnose the Damage and Pause the Bleeding
The first step in any domain warmup is not sending — it's stopping. We paused the full broadcast calendar immediately and pulled six months of send history. The pattern was unambiguous: 25% open rates in August, sliding to 20% in September, 15% in November, 10% in December, 2.23% on January 9, then 0.55% on a 64,171-send Feb 1 broadcast. Every additional broadcast to the full list was making inbox placement worse. We held broadcasts and built a list of the 95 most-engaged subscribers from the last 30 days — the customers Gmail and Apple Mail already trust as legitimate recipients. That engaged micro-segment was the seed for the warmup.
Phase 2 · Start Impossibly Small With Your Most Engaged 5%
The first two warmup sends went to just 95–96 contacts each. Yes, 95. When a domain is on the edge of blacklist territory, inbox providers are watching engagement-per-send, not volume. The only way to prove legitimacy is to send to people who are definitely going to open. Phase 1 pulled a 41.67% open rate on 96 sends. Phase 2 pulled 48.42% on 95 sends. Every open was a positive signal to the mailbox providers, and the tiny volume meant that even a single spam report wouldn't tank the reputation curve.
Phase 3 · Double the List Only When Engagement Holds
The expansion rule was simple: double the send volume only if the prior send held above 30% open rate. Phase 3 went to 273 contacts and landed at 49.45% open. Phase 4 pushed to 225 contacts at 18.67%. Phase 5 expanded again to 683 contacts at 17.72%. The open rate was trending down toward the industry baseline — that's exactly what should happen. A successful warmup does not maintain 50% open rates forever. It walks down gracefully toward the natural engagement rate of a healthy full-list send, which for cannabis dispensaries is 17–19%.
Phase 4 · Relaunch the Branded Calendar With a Targeted First Send
On February 27, after 25 days of warmup, we resumed the branded calendar with a targeted Black History Month deals send. Critically, this was still a narrowed list of 405 highly engaged contacts — not the full database. It pulled a 75.06% open rate and 31,491% ROI. That send served a second purpose beyond revenue: it was the final deliverability confirmation that the warmup had worked. Sending 405 at 75% open rate is a stronger sender-reputation signal than sending 1,900 at 25%. Inbox providers saw a legitimate marketer sending to people who wanted to hear from them.
Phase 5 · Resume Full Broadcast Cadence — and Hold It
Starting March 6, we resumed the full broadcast calendar at roughly 1,900 sends per campaign. The numbers held exactly where we wanted them: 17.92% open on Women's History Month, 17.32% on St. Patrick's Day, 19.12% on a Ruby Farms pop-up, 18.28% on a comedy-show promo, 18.17% on Easter Sale. The full-list open rate has now held above 17% for five consecutive weeks. The dispensary is sending to 97% fewer contacts than the Feb 1 broadcast and producing the same absolute number of opens — 353 opens then, 349 opens now — while burning 97% less email credit and landing in the inbox instead of promotions or spam.
Key Takeaways
Sender reputation is the silent killer of dispensary email programs. The decline from 25% open rates to 0.55% took six months of broadcasting to disengaged contacts without noticing. Most operators don't see it until it's too late because the revenue drop lags the deliverability drop by weeks. Track your full-list open rate week-over-week. If it trends down for three consecutive sends, stop broadcasting and diagnose.
The first warmup send should be 1% of your list, not 10%. The biggest mistake in domain warmup is starting too big. Sending 500 contacts at 15% open rate does nothing for your reputation — you're just producing the same low engagement signal that tanked you in the first place. Start with the 95 people who opened your last three sends. Prove high engagement on tiny volume, then expand.
Don't panic when warmup open rates come down. Phase 1 was 41.67%, Phase 5 was 17.72%. That's not failure — that's the warmup working. The engagement rate on the tiny engaged micro-segment was always going to be higher than the engagement rate on the broader list. A warmup is complete when the full-list send holds at the natural industry baseline, not when it maintains 50% open rates forever.
The same number of opens on 97% fewer sends is not a loss — it's the goal. The Feb 1 broadcast produced 353 opens from 64,171 sends. The Apr 3 broadcast produced 349 opens from 1,921 sends. Same real audience, 97% less credit burn, and inbox placement instead of promotions folder. Efficiency is the metric, not volume.
Warmup is 25 days, not 3 days. Most operators try to rescue a buried domain with a weekend of "send less and see what happens." That doesn't work. Inbox providers need to see sustained positive engagement signals across multiple sends over multiple weeks before they restore trust. Budget 3–4 weeks for a full warmup and don't rush the expansion cadence.
Need to Rescue a Buried Email Domain?
We diagnose and rehabilitate cannabis dispensary email programs that have lost sender reputation — from the first paused broadcast through a staged 5-phase warmup to a stabilized full-list cadence. If your open rate is trending the wrong direction, don't wait for it to crash.