DOCUMENTATION
Configuration Reference
Adjustable parameters and how to request configuration changes
This reference covers the PowerMTA and MailWizz configuration parameters available in your managed infrastructure. All configuration changes are applied by the Cloud Server for Email team — contact infrastructure@cloudserverforemail.com to request any adjustment.
PowerMTA Domain Block Parameters
| Parameter | Default (Production) | Range | When to Request Change |
|---|
| max-smtp-out | 5–10 per ISP | 1–20 | Reduce if deferral rate >10%; increase after sustained HIGH reputation |
| max-msg-rate | 800–3,500/h per ISP | Unlimited | Reduce if deferral spikes; increase gradually as reputation improves |
| retry-after | 15–30m per ISP | 5m–12h | Increase if ISP hints longer retry interval in 421 response |
| max-msg-per-conn | 30–100 per ISP | 1–200 | Rarely needs changing; adjust if session-termination bounces appear |
| dkim-sign | yes (all domains) | yes/no | Always yes; disable only for specific diagnostic testing |
Adding a New Sending Domain
- Email infrastructure@cloudserverforemail.com with the new domain name
- We generate DKIM key pair and provide the DNS TXT record
- Add the DKIM record to the new domain DNS
- Add the new domain IPs to your SPF record
- We configure PowerMTA domain block and MailWizz sending domain
MailWizz Key Settings
| Setting | Location | Notes |
|---|
| Suppression list | Lists → Subscriber suppression | Add hard bounces and complaints; global list applies to all campaigns |
| Bounce server | Backend → Servers → Bounce servers | Must be active; we configure IMAP connection during onboarding |
| Tracking domain | Backend → Settings → Tracking | Custom domain with SSL; configured during onboarding |
| Campaign hourly quota | Campaign → Sending quota | Must not exceed PowerMTA max-msg-rate for that ISP |
| Cron schedule | Server crontab | Every 5 minutes; do not modify without consulting us |
Requesting Configuration Changes
To: infrastructure@cloudserverforemail.com
Subject: Configuration Change Request
Parameter: max-smtp-out (gmail.com)
Current value: 8
Requested value: 6
Reason: Gmail deferral rate elevated (12%) over last 3 days
Accounting log attached: [attach excerpt]
We review and apply configuration changes within 24 business hours. Changes affecting delivery behavior are monitored for 2–4 hours after application.
Direct Configuration AccessEnterprise tier clients receive SSH access to their server. However, direct edits to /etc/pmta/config should be coordinated with the Cloud Server for Email team to avoid conflicts with monitoring and management systems.
