Demo
Demo

Knowledge base

PMTA knowledge base›Command§ 6.3.8

resolve

Resolve a name and connect
The first circle of a delivery investigation

Asks the name server for the domain’s mail route — MX records and addresses — and prints it. With –connect it also connects to the first available mail host, showing the SMTP conversation.

The manual makes it the first step of analysis when a domain’s queue grows: either half can break — name resolution or connecting to the host.

Options for different questions: –tcp and –edns — query transport, –server — another name server, –source — your own address for connecting, –use-dane and –use-mta-sts — checking by DANE and MTA-STS, –interactive — manual SMTP commands.

The main trap is calling it without the connect option. Without it the command only resolves the name and does not connect to the mail hosts: the answer “the name resolved” does not yet mean the receiver can be reached.
What the Hub does. It does not call it: the Hub sees receiver availability through accounting, and it checks the DNS of its own domains without the engine.
Recommended values

When to call it:

Question This command or not
does the domain’s mail route resolve yes
does the mail host answer our address yes — –connect –source=address
what the receiver replies to a specific message no — trace
The options, the no-connect default and its place in the analysis come from the manual (§ 6.3.8, § 4.2.2). The split of questions is ours.
Example configuration
# route and connection — from the default address and from a sending address
pmta resolve --connect outlook.compmta resolve --connect --source=203.0.113.10 outlook.com
The first line is the manual’s example. The second connects from a specific sending address, the way a real delivery will go.
yellow — — directive names, blue — blocks. They are highlighted the same way in the text of the card.
Compatibility
PowerMTA 6.0
described in the manual of this version · platform: any
The vendor does not state the first version for every directive — there is no note here. The name also appears in the 5.0 edition of the manual.
⇄

Related entries

3 relations

Works together with

The node needs a resolver that does all the work itselfThe mechanism the command works with. § 6.3.8The name lookup did not complete — and no conclusion is drawnA neighboring catalog entry. inference

Where you can see it

Figure out why a queue to one receiver is growingThe procedure in which this command is one of the steps. § 4.2.2

Referenced from

edns-udp-lengthGlobalThe name resolution command does not use this line: it has its own size option. § 3.3.1.46Check whether a message will pass the SPF checkThe SPF check relies on DNS queries; that command shows what the node’s resolver returns. inferenceRun a command over the networkThe same output from the command line. § 8.4

How to check on the node
If the name does not resolve, compare with an external name server:
dig +short MX outlook.com
dig +short MX outlook.com @1.1.1.1
Different answers mean the problem is the node’s name server, not the domain; the manual requires a recursive server for the engine.
◇

What else to read

3 articles

◇What the node tells about itself and through which channelsSeven observation surfaces: the web monitor, the console in four formats, the log, accounting, accounting search, metrics and export to external analytics.◇The watchdog that restarts the engineKeeps an eye on the engine and brings it back up after a crash by itself, sending a crash report to the postmaster address.◇What makes a virtual machine riskyRunning on a virtual machine is possible, but the manual does not recommend it without sufficient hardware and properly tuned hypervisor settings: under load the node may stop responding.

In the Hub
Cost of a mistake
safe: a wrong value breaks nothing
Scenarios
Troubleshoot deliverability · Prepare a node for sending · Untangle a stuck queue