MTAs and delivery · choosing an MTA
Both are commercial MTAs (mail transfer agents — the servers that actually deliver your email) built for high volumes, and both work with MTA-Hub. The difference is in how they are built: PowerMTA runs sending by well-tuned rules from its configuration, while MailerQ is built around RabbitMQ queues and is managed on the fly. Choose by who will be in charge of delivery — the rules or your own code.
01 / Which one for whom
Both have more than enough power: in practice your limit is set not by the MTA but by how well your IP addresses and domains are warmed up. What really decides is how you send and who controls delivery.
02 / Point by point
How they are built, how they are configured, how they react to bounces, and what the Hub does with each MTA.
| Point | PowerMTA | MailerQ |
|---|---|---|
| How it’s built | a single process, queues on disk, a text configuration | the MTA, a RabbitMQ broker and a cluster database |
| Where settings live | the configuration file and the files it includes | four layers: the process file, the control database, REST, message properties |
| Changing settings | edit the file and reload the configuration | in the database and via REST — on the fly; the process file — with a restart |
| Rules per mailbox provider | domain sections and macros: connections, rate, TLS, retries | a rate for each “IP address → domain” pair: messages, connections, bytes per minute |
| Reaction to bounces | the queue switches to a gentle (backoff) mode based on response patterns | patterns slow the flow down or change the IP address, tags and what happens to the message |
| How messages get into the MTA | SMTP and a pickup directory | SMTP, REST, straight into a RabbitMQ queue, a pickup directory |
| Delivery results | accounting files for every message | result queues: success and failure |
| Scale | high sending volume on a single server | horizontal: a cluster on shared queues and a shared database |
| With email platforms | modules in Protosender, Interspire and Mumara | through the platform’s SMTP servers |
| In MTA-Hub | installed in about 6 minutes, config from a template in Protosender format, live snapshot, accounting stats | installed part by part, database changes without a restart, snapshot from the broker queues |
| Warm-up in the Hub | the plan holds the daily volume; PowerMTA gets gentle mode for IP addresses being warmed up | the plan holds the daily volume; MailerQ’s own schedules are not used |
| License | sold separately — MailCore System | sold separately — MailCore System |
← the table scrolls sideways →
03 / One registry
The Hub manages both MTAs the same way wherever it can, and shows you honestly where they differ. So you can start with one and add the other when you need it.
PowerMTA and MailerQ nodes sit in one infrastructure and on one diagram. Your email platform gets sending points from both.
Pause, gentle mode, retry a queue, take an IP address out — you choose an action, not an MTA command. Anything the MTA can’t do is shown grayed out, with the reason.
From 0 to 100 at the level of the infrastructure, node, vMTA and IP address — with a breakdown of what dropped. Red means spam only, for both MTAs.
DNS records, signing keys, proxies and the warm-up plan don’t depend on which MTA runs on the node.
04 / Questions
Didn’t find an answer? Write to site@mta-hub.com or on Telegram.
Most often PowerMTA: these platforms’ modules are built for it. But through the Hub any of the four platforms gets sending points from nodes running either MTA — so MailerQ works for it too.
PowerMTA gets more out of a single server; MailerQ grows as a cluster. In practice your limit is set not by the MTA but by how well your IP addresses and domains are warmed up: new infrastructure starts with small volumes and grows by the warm-up plan.
PowerMTA has one process and one configuration file. MailerQ has three parts — the MTA, the broker and the database — and four layers of settings. The Hub evens out the difference: it installs all parts of MailerQ and collects a live snapshot of its queues just as it does for PowerMTA.
Yes. Both live in one Hub registry: add a node with the other MTA and it joins the same diagram and gets the same domains, warm-up and operations.
In the open knowledge bases: PowerMTA — 853 entries and MailerQ — 473 entries. These are the same catalogs that live inside the Hub.
05 / Next step
The Hub’s Specification tells you how many nodes, IP addresses and domains you need, and which MTA suits your type of sending. The estimate doesn’t commit you to anything.
More on each