Need help blocking SMTP connections based off EHLO name

Sorry, big oversight on my part. Try this one:

when CLIENT_ACCEPTED {
 TCP::respond "220\r\n"
 TCP::collect
 }

when CLIENT_DATA {
 set clientpayload [string tolower[TCP::payload]]
 if { $clientpayload contains "ehlo abcd-pc" } {
  reject
 }
}