Mailbox Governance & Delivery Deliverability Ramp
Protect your sender reputation with dual sliding rate limiters, Google OAuth 2.0 PKCE authentication, custom SMTP/IMAP failover, and progressive automated warmup scaling.
The Midnight Reset Trap
Traditional tools calculate daily send limits on a calendar basis resetting at midnight. If an engine dispatches 200 emails in 10 minutes at 00:01, destination ESPs (Google, Microsoft) flag the spike as a botnet and blacklist the IP.
Abrupt Volume Spikes
Connecting a brand new mailbox and blasting 100 emails on day one guarantees immediate spam placement. Mailboxes require progressive multi-week warmup curves to earn ISP trust.
Unmonitored SMTP Bounces
When an ESP issues a transient 421 Service not available throttle, continuing to push messages causes permanent account suspension. SiSender triggers automated cooldown pauses.
How SiSender Governs Mailbox Health
Sliding windows and automated cooldowns protect your sender reputation mathematically.
Dual-Window Meters
The dispatcher calculates limits on continuous rolling 60-minute and 24-hour windows. If the 60-minute limit is reached, outbound sends pause smoothly until capacity drains.
Automated Warmup Ramp
New accounts begin with conservative daily quotas (e.g. 10 sends/day) and automatically scale upward by pre-set daily increments until reaching the target ceiling.
OAuth & App Passwords
Connect Google Workspace seamlessly via OAuth 2.0 or integrate custom SMTP/IMAP credentials with TLS encryption for Microsoft 365, Amazon SES, or private servers.
Automated Cooldown
Upon detecting an authentication timeout or destination rate limit, SiSender pauses that specific mailbox automatically, preserving the rest of your campaign capacity.
Mailbox Governance Console
Exact rebuild of engage_deploy_CHG0107/app/Views/outreach/mailboxes/index.php displaying rolling meters, warmup progression, and provider tags.
Mailboxes
Deliverability Capabilities Ledger
| Capability | Implementation Details | Status | Code Reference |
|---|---|---|---|
| Rolling Dual-Window Gauges | Calculates sent messages over trailing 60m and 24h intervals to prevent burst rate spikes. | COMPLETE | MailboxModel.php |
| Automated Warmup Ramp | Incrementally elevates daily mailbox caps according to mathematical warmup progression. | COMPLETE | MailboxController::setLimits |
| Google OAuth 2.0 PKCE | Direct authorization flow with Google Identity, storing secure refresh tokens without password exposure. | COMPLETE | MailboxController::connect |
| Automatic Cooldown Trigger | Isolates mailboxes experiencing transient SMTP 4xx errors, setting pausedUntil timestamps. |
COMPLETE | QueueController::handleError |
| Custom Tracking Domains (CNAME) | Validates custom DNS CNAME records for tracking opens and clicks using your corporate domain. | COMPLETE | TrackingSettingsController.php |