allow_xclient
Since: Version 2025.10.06-5ec871ab
The functionality described in this section requires version 2025.10.06-5ec871ab of KumoMTA, or a more recent version.
Danger
Take care to apply this ONLY in an appropriate peer block,
otherwise you risk a variety of security/authentication related
bypasses.
When set to true, allows the connected session to use the
XCLIENT ESMTP extension.
XCLIENT is used primarily in testing environments to facilitate validation of
authentication checks that are based upon the IP address of the peer or the
server itself.
KumoMTA supports the following XCLIENT attributes:
ADDRandPORT: cause thereceived_frommetadata to change to reflect the specified address and/or port.DESTADDRandDESTPORT: cause thereceived_viametadata to change to reflect the specified address and/or port.
None of the other XCLIENT attributes are supported at the time of writing.
After XCLIENT has been successfully negotiated, the ESMTP listener
re-evaluates the parameters (especially the via and peer
blocks), and triggers
smtp_server_get_dynamic_parameters
to ensure that all the listener configuration has been updated to match the
adjusted via and from addresses.