We send an alert — or a list of mailboxes in your weekly check-in — when the warmup activity we observe on a mailbox is lower than we recommend. You'll also see it in the Mailbox Performance Summary on the Home page ("N mailboxes are sending fewer than 25 warmup emails per day") and in the Mailbox volume section of Insights. If your warmup tool shows a healthy target, the alert isn't contradicting you — it measures what the mailbox actually does, not the number in the settings.
Settings vs. actual activity
The number in your warmup settings is a target — the maximum warmup emails per day.
The alert is based on the warmup emails actually sent and received over the recent period.
Our recommendation for Maildoso SMTP mailboxes is 80 warmup emails per mailbox per day from day one, with slow ramp-up / increment per day disabled (50/day in tools that cap at 50, such as Plusvibe and EmailBison). A mailbox running below that triggers the alert. See How warmup works and how to start it.
Google Workspace mailboxes are the exception: they warm at 25/day with an increment of 2–3 per day, so a Workspace mailbox climbing towards 25 is expected.
Common reasons real activity is lower than recommended
Slow ramp-up (increment per day) is enabled, so a new mailbox is climbing from a low number instead of starting at 80. On Maildoso SMTP mailboxes this isn't needed.
The target itself was set below 80 — for example a sequencer's default of 20–50/day was left in place.
Warmup was paused, or the mailbox was disconnected from the warmup tool and needs reconnecting.
The mailbox's domain finished provisioning only recently, so warmup started later than the rest of the batch.
Warmup runs in an external tool whose own schedule or throttle is lower than the target.
What to do
Look at the actual per-mailbox numbers (in the list we sent, in Insights → Mailbox volume, or in your tool's warmup statistics), not just the target.
Disable slow ramp-up and set the target to 80 (or the tool's maximum) right away, including on mailboxes less than two weeks old — there's no ramp-up phase to wait out on SMTP mailboxes.
If a mailbox shows as disconnected or has stopped sending warmup, reconnect it in the tool.
"My tool caps warmup at 50" isn't why a mailbox is flagged. Flagged mailboxes are almost always well below 50 — for example 10, 20 or 40 a day. Raise them to the cap first.
While warmup is below the recommendation, keep campaign sending at or below 15/day per mailbox (10/day in tools capped at 50). Low warmup combined with high campaign volume is the most common cause of deliverability problems, so lower the campaign side rather than leaving warmup low.
Don't push the target above 80 to make up for lost days — 80 is the ceiling for SMTP mailboxes, and total sending is capped at 100/day.
If it still doesn't add up
Send us the affected mailbox addresses, the warmup tool you use, and your daily campaign volume, and we'll tell you whether the settings need changing or something is genuinely wrong. If your sequencer disabled warmup entirely rather than just flagging it as low, see Verification and reactivation codes from your sequencer.