If the SUNs do indeed only send <LF> at the end of the HELO line (and other
lines in the SMTP protocol), then they are not following the protocol as
specified by the Network Information Center. From NIC:<RFC>RFC821.TXT:
The following two commands are used in transmission channel
opening and closing:
HELO <SP> <domain> <CRLF>
QUIT <CRLF>
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