docs: unblock Mailcow — move to Billing VPS, remove Frostwall dependency

Decision: Mailcow goes on Billing VPS (38.68.14.188) not NC1.
Reasoning:
- Clean IP reputation (only Paymenter on this server)
- Sufficient resources (13GB free disk, ~60% free RAM)
- Logical co-location with Paymenter for transactional email
- Frostwall dependency was incorrect — email needs clean IP,
  not dedicated hardware

Mailcow is now unblocked and ready to deploy.

Session: Chronicler #30

docs/core/tasks.md

@@ -477,15 +477,21 @@ Self-hosted AI assistant providing 24/7 support to all community tiers. "Most Mi
 
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-### 11. Mailcow Email Server on NC1
+### 11. Mailcow Email Server on Billing VPS
 **Time:** 2-3 hours  
-**Status:** BLOCKED  
-**Depends:** NC1 cleanup ✅, Frostwall Protocol  
+**Status:** READY — Frostwall dependency removed (March 14, 2026)  
+**Depends:** Nothing — unblocked  
 **Documentation:** `docs/tasks/mailcow-email-server-on-nc1/`
 
-Professional @firefrostgaming.com email on NC1. Self-hosted, $120/year saved, eliminates Plesk.
+Professional @firefrostgaming.com email on Billing VPS. Self-hosted, $120/year saved, eliminates Plesk.
 
-**Location:** NC1 Charlotte (32-core EPYC, 251GB RAM)
+**Location:** Billing VPS (38.68.14.188) — clean IP, shares with Paymenter only
+**Previous Location:** NC1 Charlotte (incorrect — game server IP reputation risk)
+
+**Decision (March 14, 2026):** Moved from NC1 to Billing VPS. Frostwall dependency was based on
+incorrect assumption that Mailcow needed dedicated hardware. Actual requirement is clean IP reputation.
+Billing VPS has clean IP, sufficient resources (18GB disk, 40% memory headroom), and logical
+co-location with Paymenter for transactional email.
 
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