A NimbusOS campaign carries a campaign_type field that governs its behavior throughout its entire lifecycle. Four types are supported: cold_outreach, nurture, re_engagement, and warmup. Picking the wrong type does not break anything obvious, but it silently unlocks or restricts the wrong throttles, gates, and downstream automations. This article explains what each type does and when to use it.
The Four Types at a Glance
| Type | Prospect relationship | Deliverability gate | Throttle | Typical use |
| ---- | -------------------- | ------------------ | -------- | ----------- |
| cold_outreach | No prior contact, no consent | Strict resume gate | Aggressive | New prospect outreach |
| nurture | Prior engagement or consent | Loose | Moderate | Lead nurturing, drip |
| re_engagement | Went cold after prior activity | Moderate | Cautious | Win back dormant leads |
| warmup | Partner network only | Not applicable | Internal | Sending fleet warmup |
cold_outreach
The type you reach for when running new prospect outreach to contacts who have no prior relationship with your business. The deliverability brain applies its strictest rules to this type.
Strict resume gate
Before a cold outreach campaign launches, the resume gate checks three conditions: 20 inboxes at stage 3 or higher, 25 percent of the fleet at stage 3 or higher, and 7 day bounce rate under 2 percent. All three must be true. The gate is documented in detail in the Email Warmup article.
Aggressive bounce and complaint thresholds
A cold outreach campaign auto pauses at:
- bounce rate over 2 percent in 24 hours
- spam complaint rate over 0.1 percent in 24 hours
- unsubscribe rate over 2 percent in 24 hours
Auto pause fires within one sending cycle, which is typically under 15 minutes. The campaign owner receives an alert with the specific threshold that tripped.
ICP aware rate limiting
The engine caps max_new_leads_per_day based on the target segment's average ICP tier. A segment of mostly tier A contacts gets a higher default cap than a segment of mostly tier C contacts. This prevents a dirty low-tier list from burning reputation at scale.
Full reply classification and Growth Brain sync
Every reply runs through the reply intelligence classifier. Anonymized performance data feeds the Growth Brain. This is where the collective intelligence signal comes from.
When to use cold outreach: any campaign where the recipient does not reasonably expect your email. A CSV of LinkedIn scraped prospects, an Apollo search result, a competitor poaching list. All cold outreach.
nurture
The type for contacts who have given some signal of interest or consent. A demo request that did not convert, an ebook downloader, an event attendee, a previously engaged customer who has gone quiet but not fully cold.
Loose deliverability gate
Nurture campaigns do not hit the cold outreach resume gate. They can launch on a fleet that is still maturing, as long as inboxes are at stage 2 or higher. The assumption is that a prior engagement relationship carries lower deliverability risk.
Moderate throttle
Bounce threshold 3 percent, complaint 0.2 percent, unsubscribe 3 percent. All higher than cold outreach because a nurture audience is typically more engaged and can tolerate more touches without triggering spam complaints.
Longer send windows allowed
Nurture campaigns can schedule sends outside standard business hours because the audience has a preexisting relationship. Weekend sends are allowed (though still not recommended for most industries).
When to use nurture: a post demo follow up series, a webinar attendee drip, a dormant customer win back, a newsletter style outbound to an opt-in list.
re_engagement
A specialization of nurture for contacts who were previously active and have gone dormant. The re_engagement type exists because the sending posture for dormant contacts is subtly different from active nurture.
Strict list hygiene
A re_engagement campaign runs a mandatory email verification pass on the target segment at launch time. Dormant contacts often have stale emails, and a re_engagement send to an invalid address is worse than a cold send because it looks suspicious to ISPs after the prior engagement.
Smaller batch sizes
The daily cap defaults to 50 percent of what you would set for a nurture campaign. The logic: re-engagement needs care. Low volume, high personalization, strong subject lines.
Mandatory unsubscribe link
Every re_engagement email includes an unsubscribe link in the body (not just the header). This is both good practice and a CAN-SPAM alignment gesture.
When to use re_engagement: a 6-month dormant customer outreach, a win-back sequence, a "we noticed you haven't logged in" email track.
warmup
The internal type used by the warmup engine. You do not create warmup campaigns directly. They exist so the sending fleet has a conversational training ground with the warmup partner network.
Warmup campaigns are invisible in the campaigns list by default. A filter toggle reveals them for debugging. Sends, replies, and reputation events are recorded but do not count against your workspace's send quotas.
If a warmup campaign shows up in an unexpected place (like appearing in a client report), hide it from the client portal through the ClientPortalConfig.visibility_rules.
Platform Choice Interacts with Type
Each campaign also picks a platform field: ReachInbox, Smartlead, Instantly, Lemlist, or native. The combination of type and platform determines what happens at send time.
A cold_outreach campaign on ReachInbox runs the full pipeline: resume gate, rotation across stage 3 plus inboxes, reply sync through the ReachInbox webhook.
A cold_outreach campaign on Smartlead or Instantly pushes the campaign definition down to the external platform. The resume gate still runs on the NimbusOS side before enabling the downstream campaign. Reply sync flows back through the platform's integration.
A nurture campaign on native (Gmail or Microsoft 365 OAuth) runs without ReachInbox in the path. Lower volume ceiling but full control.
The right combination is workspace specific. Most agencies use cold_outreach + ReachInbox as the default and nurture + native for their high value post-demo drips.
Stop Conditions by Type
Every type respects its own default stop condition pattern.
cold_outreach. stop_on_reply=true by default. stop_on_domain_reply is off but frequently enabled for multi stakeholder outreach. The sequence halts immediately on any reply.
nurture. stop_on_reply=true but only for the current thread. A reply to a nurture email pauses the drip for 14 days and then allows it to resume. The logic is that a nurture reply is a conversation, not a campaign exit.
re_engagement. stop_on_reply=true and the contact is flagged as re-engaged, which moves them to the active segment for nurture going forward.
warmup. Not applicable; warmup campaigns self-manage stop conditions internally.
Campaign Type and A/B Testing
You can A/B test subject lines, openers, and send windows within a single campaign. You cannot A/B test across campaign types. Comparing a cold outreach to a nurture campaign is not a valid A/B test because the audiences and deliverability postures differ.
If you want to test cold versus nurture framing for the same prospect population, consider running two campaigns of the same type with different copy, rather than two campaigns of different types.
Analytics Segmentation by Type
The analytics dashboard supports filtering by campaign type. Key benchmarks to watch:
Cold outreach: 40 to 60 percent open rate, 3 to 8 percent reply rate, under 2 percent bounce rate.
Nurture: 30 to 50 percent open rate, 5 to 15 percent reply rate, under 1 percent bounce rate.
Re-engagement: 20 to 40 percent open rate, 4 to 10 percent reply rate, under 2 percent bounce rate.
These are benchmarks, not targets. A healthy cold outreach campaign to a tier A segment can exceed 70 percent open rate. A cold outreach campaign to a tier C segment might sit at 25 percent and still generate pipeline.
Mistakes to Avoid
Running a cold outreach campaign labeled as nurture. Skips the resume gate, burns reputation, the platform cannot protect you because the type says the audience is opted in.
Running a nurture campaign labeled as cold_outreach. The gate blocks launch even though the audience is safe. The platform is being conservative but is blocking work you could have shipped.
Using re_engagement for active customers. Active customer communication belongs in a transactional or product email system, not in NimbusOS. Re_engagement is for dormant relationships, not active ones.
Manually creating a warmup campaign. The warmup engine owns this type. Manual creation is not validated for the correct send patterns and will produce bad warmup signals.
Frequently Asked Questions
Can I change a campaign's type after launch?
Yes, with caveats. Changing from cold_outreach to nurture mid campaign does not re-run the resume gate, but it changes the downstream throttle and alert thresholds. Document the change; it affects the historical metrics of the campaign.
How does the campaign type interact with per-inbox campaign restrictions?
If an inbox is restricted to nurture only, it will not serve cold_outreach campaigns regardless of which campaign the rotation selects. The inbox restriction wins.
Does the platform recommend a type based on the segment?
Not automatically. You can see a recommendation on the campaign creation screen if the platform detects a mismatch. For example, if 80 percent of the target segment has a prior engagement record, the platform suggests nurture rather than cold_outreach.
Is there a fifth type I am missing?
No. Four types cover the full lifecycle of B2B outbound. Multichannel campaigns (which include LinkedIn and SMS) are a separate object model rather than a fifth type on Campaign.
What to Read Next
After picking the right type, useful next reads are Sequence Builder for structuring the step flow, Campaign Analytics for reading performance by type, and Deliverability Overview for the brain that enforces the type specific rules.