我们使用“Google Apps for Your Domain”发送电子邮件，但希望使用我们的旧电子邮件服务器发送邮件。原因是我们的几个合作伙伴将 Google Apps SMTP 列为垃圾邮件 (!!)。
Google 有关于配置此选项的详细说明，但我对 SPF 不是 100% 熟悉，当然也完全没有使用 MailEnable 的经验。MailEnable 似乎强制您指定单个 IP 范围以允许而不是范围，即使我遵循了配置 SPF 的说明并浏览了他们的知识库。
我试过设置，但 MailEnable 不允许谷歌中继邮件：
Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the recipient domain.
We recommend contacting the other email provider for further information about the
cause of this error. The error that the other server returned was: 503 503 This mail
server requires authentication when attempting to send to a non-local e-mail address.
Please check your mail client settings or contact your administrator to verify that
the domain or address is defined for this server. (state 14).
有关如何进行的任何 MailEnable 建议？