Configuration Guide Top: Powermta
<virtual-mta vmta-transactional> smtp-source-host 192.0.2.10 host-name mx1.transactional.example.com max-msg-rate 50000/h domain-key trans_sel, transactional.example.com, /etc/pmta/dkim/transactional.pem </virtual-mta>
Mailbox providers reject unauthenticated emails immediately. PowerMTA handles DKIM signing natively within the configuration file. Implementing Native DKIM Signing
<bind source-vmta="gmail-ip1" destination-domain="gmail.com"> source-interface 192.0.2.10 max-smtp-out 20 max-smtp-out-per-ip 4 <dkim> sign yes selector 2024 domain senderdomain.com key-file /etc/pmta/dkim/sender.key </dkim> </bind>
pmtad --debug
| MTA | License | Architecture | Native IP Pools | Scriptable | Best suited for | | --- | --- | --- | --- | --- | --- | | | Commercial | Java (JVM) | ✅ (vMTA) | ❌ | Large enterprises requiring commercial support and battle‑tested reliability | | KumoMTA | Open Source (Apache 2.0) | Rust (async) | ✅ (Lua) | ✅ (full Lua) | Technical teams seeking PowerMTA‑grade features without license fees | | Postfix | Open Source | C (multi‑process) | ❌ (requires external tools) | ❌ | General‑purpose inbound/outbound mail, internal relays | | Haraka | MIT | Node.js (event loop) | ✅ (plugin) | ✅ (JavaScript) | Developers comfortable maintaining their own MTA infrastructure |
max-msg-rate 500/s max-smtp-out 1000 log-file /var/log/pmta/acct.log Use code with caution. 3. Domain-Specific Throttling and Queue Management
/usr/sbin/pmta reload
disk-queue /var/spool/powermta memory-pool-buffer-size 2m
<domain yahoo.com> max-smtp-out 15 max-smtp-out-per-ip 3 max-messages-per-connection 50 concurrency 15 <limits> throttle 500/minute </limits> </domain>
A solid foundation prevents many common problems later. powermta configuration guide top
If you are setting this up for a specific scale or use case, let me know: What do you plan to send daily?
<domain *> enable-starttls yes require-starttls no tls-certificate-file /etc/pmta/cert.pem tls-private-key-file /etc/pmta/key.pem </domain>
Different ISPs have different thresholds for connection velocity. Gmail may allow hundreds of concurrent connections, while Yahoo will temporarily block (defer) you if you open more than a few connections at once. <virtual-mta vmta-transactional> smtp-source-host 192