For some repository URL (such as `scpexe`), Maven may require additional configuration (such as user name, executable path, etc.) Maven wants you to specify this in `~/.m2/settings.xml` of the user that runs Jenkins, and this ID value is used to retrieve the setting information from this file (that is, the <server> element with this ID value will be consulted for various protocol-specific configuration values.)

See the maven-deploy-plugin usage page for more details.