请教500错误是什么意思？

encourage52

请教一下这是为什么？小第我才接触，希望以后大家多多指点，谢谢了
香港公司發我們的郵件會出現500 error的退信,MD日志有下列記載,香港公司使用的是UNIX的郵件系統


Fri 2006-10-13 10:01:11: <-- MAIL FROM:<[email=LB@*.hk]LB@*.hk[/email]> SIZE=433777
>Fri 2006-10-13 10:01:11: --> 250 <[email=LB@*.hk]LB@*.hk[/email]>, Sender ok
>Fri 2006-10-13 10:01:12: <-- RCPT TO:<[email=lb@*.com]lb@*.com[/email]>
>Fri 2006-10-13 10:01:12: --> 250 <[email=lb@*.com]lb@*.com[/email]>, Recipient ok
>Fri 2006-10-13 10:01:12: <-- DATA
>Fri 2006-10-13 10:01:12: Creating temp file (SMTP):
>d:\mdaemon\queues\temp\md50000070164.tmp
>Fri 2006-10-13 10:01:12: --> 354 Enter mail, end with <CRLF>.<CRLF>
>Fri 2006-10-13 10:01:22: Winsock Error 10054 Connection was reset by the
>other side!
>Fri 2006-10-13 10:01:22: SMTP session terminated (Bytes in/out: 385655/328)
>Fri 2006-10-13 10:01:22: ----------