Connection timed out

To support,

I am running a linux mail server and I got error message when we send email to some of the customer .   Those customer is using your mail filtering service .   Error message is

connect to cluster4a.us.messagelabs.com[216.82.251.230]:25: Connection timed out

Our server ip is 218.213.150.105

Please help to check and release our ip for blocking.

regards,

Michael