三,当英特网用户发送邮件至此三人,
错误信息是:
The following message to <UserB@xyz.com> was undeliverable.
The reason for the problem:
5.1.0 - Unknown address error 550-'Requested mail action not taken: Invalid IP'
The following message to UserA@xyz.com was undeliverable.
The reason for the problem:
5.1.2 - Bad destination host 'DNS Hard Error looking up berstoff.com.cn (MX): NXDomain'