External identifier and description

You can use the following optional MIME headers to define your own identifier and/or a description:

  • X-Clab-SmartRelay-ExternalId
    • Your own identifierAny positive integer.
  • X-Clab-SmartRelay-ExternalDesc
    • Your own descriptionAn alphanumeric string of up to 255 characters


You can use none, one or both of these headers. Their values can be entirely unrelated.

SmartRelay stores the header values in the database, together with other data about the relevant message. They can be found in the detailed message data, in the appropriate DataExporter feed.


Session session = Session.getInstance( System.getProperties(), null );<br />
Message msg = new MimeMessage( session );<br />
msg.setHeader( "X-Clab-SmartRelay-ExternalId", "23" );<br />
msg.setHeader( "X-Clab-SmartRelay-ExternalDesc", "Testing only" );<br />


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Storing recipient addresses in a user database