The following example extracts SMTP content from a flow.

function Flow_GetSmtpContentInFlow (dpiMessage, ruleEngine)
  require 'LOG'
  local my_application = GetLatestApplication(dpiMessage)
  if my_application == 'smtp' then
    local smtp_content = GetSmtpContent(dpiMessage)
    if smtp_content ~= nil and smtp_content ~= '' then
      -- smtp_content contains data from the SMTP flow.
    else
      EZINFO('Empty SMTP content')
    end
  end
end