JSON for incoming messages

When an email is received by MailerQ, the mail is turned into a JSON object and published to the inbox queue. This happens to messages that are received on the SMTP port, but also to messages that come in via the spool directory or that were injected via the command line interface: every message is turned into a JSON object and published to the inbox queue.

The JSON messages that are published by MailerQ follow exactly the JSON specification for outgoing messages. It is therefore possible to let MailerQ publish these incoming messages directly to the outbox queue to deliver them to the final recipient.

MailerQ shared inbox outbox queue

MailerQ also adds some extra properties to the JSON of incoming messages that are not needed for the delivery of the email, but that are useful in case you write scripts or programs that process incoming messages. The following properties can be found on incoming messages:

hostname server name that received the message
received time when the mail was received
message-id unique message id generated for the mail (only used when received via smtp)
connection connection info (only used when received via smtp)
spool spool info (only used when received from spool dir)
cli command info (only used when received from cli)
checks array with the results of the SPF, DKIM and DMARC checks

The above properties are never used by MailerQ when the email is sent, but they can be useful to recognize incoming messages.

Message ID, hostname and timestamp

When a connection comes in over an SMTP connection, MailerQ reports a unique internal identifier to the sender that can be used to track the email.

250-Ok, your message has been queued using the following identifiers:
250 gdsfu232 for info@example.com

Every recipient gets a unique identifier. This unique identifier is stored in the "message-id" property.

{
    "message-id": "gdsfu232",
    "received": "2016-03-22 17:23:12",
    "hostname": "sender1.mailerq.com",
    "envelope": "whatever@example.com",
    "recipient": "info@example.com",
    "mime": "..."
}

The "received" property holds the time when the email was received, while "hostname" holds the name of the server that received the message. These two properties are included for all injection mechanisms: SMTP, CLI, and spool.

TCP connection data

If the mail came in via an SMTP connection, the generated JSON object holds properties about the TCP connection.

{
    "message-id": "gdsfu232",
    "received": "2016-03-22 17:23:12",
    "hostname": "sender1.mailerq.com",
    "envelope": "whatever@example.com",
    "recipient": "info@example.com",
    "mime": "...",
    "connection": {
        "local-ip": "1.2.3.4",
        "local-port": 25,
        "remote-ip": "5.6.7.8",
        "remote-port": 25324,
        "secure": true,
        "user": "mailerq"
    }
}

If MailerQ runs behind a HAProxy server, the connection data is extracted from the PROXY header that is sent by the HAProxy server.

If the TCP connection is secure and some sort of SMTP authentication mechanism was used, the "user" property holds the username of the user who submitted the message.

Spool directory data

For mails injected to the spool dir, the JSON holds properties that identify the file from which the message was loaded.

{
    "received": "2016-03-22 17:23:12",
    "hostname": "sender1.mailerq.com",
    "envelope": "whatever@example.com",
    "recipient": "info@example.com",
    "mime": "...",
    "spool": {
        "directory": "/path/to/directory",
        "file": "filename.mime",
        "user": "owner",
        "size": 23299
    }
}

The properties speak for themselves: the spool directory path, name, owner and size of the injected file.

Command line interface

Message injected via MailerQ as command line utility hold information about the started program:

{
    "received": "2016-03-22 17:23:12",
    "hostname": "sender1.mailerq.com",
    "envelope": "whatever@example.com",
    "recipient": "info@example.com",
    "mime": "...",
    "cli": {
        "command": "/usr/bin/mailerq",
        "arguments": [ "--extract-recipients", "--ignore-dot" ],
        "user": "john"
    }
}

In the above example, the email was injected using MailerQ as command line utility. The program was started by user "john", and two options were passed: "--extract-recipients" and "--ignore-dot".

Check results

If you enable checks for incoming messages, MailerQ runs SPF, DKIM and DMARC checks on each incoming message. The result of these checks are added to the JSON.

{
    "message-id": "gdsfu232",
    "received": "2016-03-22 17:23:12",
    "hostname": "sender1.mailerq.com",
    "envelope": "whatever@example.com",
    "recipient": "info@example.com",
    "mime": "...",
    "connection": {
        "local-ip": "1.2.3.4",
        "local-port": 25,
        "remote-ip": "5.6.7.8",
        "remote-port": 25324,
        "secure": true,
        "user": "mailerq"
    },
    "checks": [ {
        "spf": "pass",
        "smtp.mailfrom": "whatever@example.com"
    }, {
        "dkim": "pass",
        "domain": "example.com",
        "selector": "dkim",
        "header.i": "fsjfksjfslkdf",
        "header.b", "sodfidjsfdsjfsfjs"
    }, {
        "dmarc": "pass",
        "header.from": "whatever@example.com"
    } ]
}

The properties for each test depend on the type of test, and hold the input parameters that were used to execute the test.

The checks are only executed for messages that are injected via SMTP, and only if checks are enabled in the config file using the "smtp-check" variable.