Primary & Satellite Topology

Core principle

Primaries are the mailboxes whose reputation matters for cold outreach.
Satellites exist only to generate realistic, controlled engagement with primaries.

                    ┌─────────────────┐
                    │ Primary         │
                    │ hello@fillcare  │
                    └────────┬────────┘
                             │
         ┌───────────────────┼───────────────────┐
         │                   │                   │
    ┌────▼────┐        ┌────▼────┐        ┌────▼────┐
    │Satellite│        │Satellite│        │Satellite│
    │ Gmail 1 │        │ Yahoo   │        │ Live    │
    └─────────┘        └─────────┘        └─────────┘

Traffic rules

Direction	Allowed	Notes
Satellite → Primary	Yes	Main warmup send
Primary → Satellite	Yes	Reply to satellite (completes thread)
Satellite → Satellite	No	Wastes quota; looks unnatural
Primary → Primary	No	Never warm primaries against each other
Satellite → unrelated external	No	Only campaign-assigned primaries

Multi-primary support

One operator can run N campaigns concurrently:

Campaign A: primary=hello@fillcareapp.com  ← satellites [gmail1, yahoo1, live1]
Campaign B: primary=sales@otherdomain.com ← satellites [gmail2, yahoo2]

Satellites may be shared across campaigns only if explicitly enabled (default: dedicated per primary to avoid cross-brand leakage).

FillCare example setup

Mailbox	Role	Provider
hello@fillcareapp.com	Primary	Google Workspace
personal@gmail.com	Satellite	Gmail
personal@yahoo.com	Satellite	Yahoo
personal@live.com	Satellite	Outlook
(+ 1–2 more)	Satellite	Mixed

Minimum viable pool

1 primary + 2 satellites (technical minimum)
Recommended: 1 primary + 4–6 satellites for natural variety and reply distribution

Satellite lifecycle

stateDiagram-v2
    [*] --> Unassigned: Add mailbox
    Unassigned --> Active: Assign to campaign
    Active --> Paused: Operator pause
    Paused --> Active: Resume
    Active --> Error: Auth/IMAP failure
    Error --> Active: Fix + test
    Active --> Unassigned: Remove from campaign

Add / remove operations

Add satellite

POST /mailboxes with role: satellite
Test SMTP/IMAP
POST /campaigns/:id/satellites to assign

Remove satellite

DELETE /campaigns/:id/satellites/:mailboxId — stops new sends
In-flight threads complete or timeout
Optional: DELETE /mailboxes/:id if fully removed

Add primary

POST /mailboxes with role: primary
POST /campaigns with recipe + bounds
Assign satellites
Start campaign (status: active)

Peer network (phase 3 — optional)

When enabled, additional engagement from vetted peer mailboxes:

Aspect	Own satellites	Peer network
Control	Full	Limited
ESP risk	Lower	Higher (pool quality)
Cost	User supplies accounts	Platform fee
Detection	User responsible	Platform must maintain pool health

Recommendation: Ship own-satellite-only first. Peer network requires bounce monitoring, DNS validation, and pool rotation — significant ops burden.

Dispatcher pairing (target logic)

for each campaign where status=active:
  if today.sends < schedule.plannedSends:
    satellite = pickWeighted(campaign.satellites)
    primary = campaign.primaryMailbox
    queueSend(from=satellite, to=primary)

Reply path (rescuer):

if shouldReply(campaign.replyRatePercent):
  reply(from=primary, to=satellite, inReplyTo=original)

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