I have search thru all the posts before posting this. I'm on Zimbra 7.2 and have updated the Zimlet to version 3.7.

The proxy error can be easily overcome by the very troublesome adding of these command lines using the CLI console for each and every COS we have one by one (example below is for our COS: g10):

zmprov mc g10 +zimbraProxyAllowedDomains twitter.com
zmprov mc g10 +zimbraProxyAllowedDomains *.twitter.com
zmprov mc g10 +zimbraProxyAllowedDomains *.facebook.com
zmprov mc g10 +zimbraProxyAllowedDomains *.linkedin.com
zmprov mc g10 +zimbraProxyAllowedDomains *.digg.com
....

With that, I manage to get Twitter to works. But Digg and Facebook are not working. Was told that if I downgrade the Zimlet to version 2.x, Facebook will works. Any other workaround???