发信问题

ZSQHERO

各位好:下面TELNET的看不懂,The letter head is null看不懂,不知什么意思,导致发不了邮件.
220 AntiSpam v2.0 ESMTP
ehlo thx8888.com
250-MAIL.SANXING.COM
250-PIPELINING
250-STARTTLS
250-AUTH LOGIN CRAM-MD5 PLAIN
250-8BITMIME
mail from:xnb@thx8888.com
250 ok
rcpt to:yanfeng@auxgroup.com
250 ok
data
subject:test
This is a test mail.
.
552 Your letter head is null.

失去了跟主机的连接.