Demo
Demo

Knowledge base

PMTA knowledge base›Procedure§ 4.2.4

Troubleshooting mail reception

Troubleshooting Email Reception/SMTP Feeding Problems
The same tracing, but on the incoming side

Message receiving rarely breaks, and almost always with a home-grown submitting program; the most common error is lines ending with a single LF instead of a CRLF pair.

It is diagnosed with a session recording of one source: a <source> block for the submitting program’s address with log-connections and log-commands shows at which step the transfer fails, and log-data shows every byte with its hexadecimal code. After a reload, the submission is reproduced, the log is read and the block is removed.

The main trap is forgetting to remove the block. The recording does not expire by itself: log-data will keep writing every byte of every submission from this address until the block is deleted.
What the Hub does. The Hub does not enable logging — it is turned off in the templates. Troubleshooting reception, like troubleshooting delivery, is done by hand on the node.
Recommended values

Recording levels:

Line What it shows
log-connections connections and their end
log-commands at which command the failure happens, for example RCPT
log-data bytes: a lone LF, non-printable characters
The most common error, the recording block and the levels come from the manual (§ 4.2.4, § 3.3.7.64–3.3.7.66). The table is ours.
Example configuration
<source 127.0.0.1>
    log-connections yes
    log-commands yes
    log-data yes</source>
An example from the manual; the address is replaced with the submitting program’s address.
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

6 relations

Does not work without

log-connections<source>The directive this step sets. § 4.2.4log-commands<source>The directive this step sets. § 4.2.4log-data<source>The directive this step sets. § 4.2.4Apply a changed configuration without stoppingThe command that performs the step. § 4.2.4

Depends on

How the node selects a source and combines its settingsThe mechanism this step relies on. inference

Where you can see it

The line ending requirementThe mechanism this step relies on. § 4.2.4

How to check on the node
Reproduce the submission and find it in the log:
pmta reload
tail -100 /var/log/pmta/log
The last command before the break is the step where submission fails; 0a codes without 0d before them are lone LFs.
◇

What else to read

3 articles

◇Who is allowed to submit mail and for whom to accept itOut of the box, the node accepts submission only from the machine itself; two different questions — “who can send through us” and “for whose addresses we accept mail” — are answered by different directives.◇How a message gets into the engineSix described submission methods: extended SMTP, four language bindings and a directory the node watches on disk.◇Two inbound report processors and what to do with themBounces by message and complaints are parsed by two identically structured blocks; each has its own address list and its own pair of decisions about the message’s fate.

In the Hub
Cost of a mistake
reversible: harms only while it is set
Scenarios
Receiving inbound mail · Connect a sending platform