messagelabs.com Connection timed out

Hello

We're experiencing problems when sending to email addresses that use messagelabs.com MX. See below;

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

I tried to connect by telnet...

This is happening for various accounts on our server which is sending from IP Address 52.187.61.132

I have used this;

http://ipremoval.sms.symantec.com/lookup/

to check on our IP and it tells there is no problem with the IP Address.

The IP address you submitted, 52.187.61.132, does not have a negative reputation and therefore cannot be submitted for investigation.

Can you please help us resolve this issue as it's causing me headaches!

Thanks