In the next example postfix does not pass HELO from XCLIENT line to the milter if "EHLO spike.porcupine.org" is ommited. It looks like bug.
220 server.example.com ESMTP Postfix EHLO client.example.com 250-server.example.com 250-PIPELINING 250-SIZE 10240000 250-VRFY 250-ETRN 250-XCLIENT NAME ADDR PROTO HELO 250 8BITMIME XCLIENT NAME=spike.porcupine.org ADDR=168.100.189.2 HELO=spike.porcupine.org 220 server.example.com ESMTP Postfix EHLO spike.porcupine.org ^^^^^^^^^^^^^^^^^^^^^^^^ 250-server.example.com 250-PIPELINING 250-SIZE 10240000 250-VRFY 250-ETRN 250-XCLIENT NAME ADDR PROTO HELO 250 8BITMIME MAIL FROM:<wie...@porcupine.org> 250 Ok RCPT TO:<u...@example.com> 250 Ok DATA 354 End data with <CR><LF>.<CR><LF> . . .message content. . . . 250 Ok: queued as 763402AAE6 QUIT 221 Bye