kumomta/docs/reference/connectionmeta.md

Connection Metadata Object

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This object represents a collection of metadata keys and values that are associated with an established incoming SMTP connection.

KumoMTA populates a small number of predefined fields (see below), and allows your policy scripts the ability to read those values as well as write (and read!) additional values as needed by the local policy. For instance, you may decide to compute a value after EHLO has been processed by smtp_server_ehlo and access that value in a later SMTP event handler.

Prior to calling smtp_server_message_received, KumoMTA will copy the values from the connection metadata and use those to populate the message metadata.

The get_meta and set_meta methods shown below are used to read and write metadata values.

Predefined Connection Metadata Values

The following values are predefined by KumoMTA:

Name	Purpose	Since
reception_protocol	indicates the reception protocol, such as ESMTP	{{since('2023.08.22-4d895015', inline=True)}}
received_via	indicates the IP:port of the KumoMTA listener that is handling this session	{{since('2023.08.22-4d895015', inline=True)}}
received_from	indicates the IP:port of the sending or peer machine in this session	{{since('2023.08.22-4d895015', inline=True)}}

Available Methods

conn_meta:get_meta(name)

Returns the value associated with name, or nil if no such value has been defined. Values may be predefined by KumoMTA, or may be set by policy scripts using conn_meta:set_meta().

conn_meta:set_meta(name, value)

Sets the value associated with name to value. Value must be serializable as JSON; it can be simple strings or numbers, but may also be an array or object value.