Regarding your issue, it was caused from the recipient mail server
(abc-cn.com) not accepting the message for the below reason:"
Connected to 211.148.xxx.xxx but connection died. (#4.4.2)
211.148.xxx.xxx does not like recipient. Remote host said: 551 User not local; please try <forward-path>". I can assure you that this was not an issue cause from Messagelabs. It seems there is a connection problem from abc-cn.com for the first attempt. In addition, once Messagelabs connected to you mail server, it was bounced back with the above error message. It was an error message generated from abc-cn.com's mail server, so we did not know what it was the caused of error. Kindly see below trace logs for detail, and this will need to be investigate from abc-cn.com's end. If you have any further questions, feel free to contact us anytime.