Happening to google too! (Score 2, Informative)

Google is getting blocked to spam too:

This is an automatically generated Delivery Status Notification

Delivery to the following recipient failed permanently:

[an address forwarded to gmail.com]

Technical details of permanent failure:
PERM_FAILURE: SMTP Error (state 10): 554 Service unavailable; Client host [64.233.184.203] blocked using bl.spamcop.net; Blocked - see http://www.spamcop.net/bl.shtml?64.233.184.203

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The address: 64.233.184.203 is wproxy.gmail.com