Some people complained that they get this message when they open facebook:

I asked the people if they ever received mails from facebook – they said “regularly”. So I wasn’t really sure what could cause this issue.

So I grepped the logs from our mail servers and found…

Dec 13 15:09:49 NOQUEUE: reject: RCPT from outmail018.snc1.tfbnw.net[69.63.178.177]: 554 5.7.1 Service unavailable; Client host [69.63.178.177] blocked using bl.spamcop.net; Blocked - see http://www.spamcop.net/bl.shtml?69.63.178.177; from=<notification+h_hj_jwm@facebookmail.com> to=<xxx> proto=ESMTP helo=<mx-out.facebook.com>
Dec 12 12:45:26 NOQUEUE: reject: RCPT from outmail017.snc1.tfbnw.net[69.63.178.176]: 554 5.7.1 Service unavailable; Client host [69.63.178.176] blocked using bl.spamcop.net; Blocked - see http://www.spamcop.net/bl.shtml?69.63.178.176; from=<notification+ori=gczf@facebookmail.com> to=<xxx> proto=ESMTP helo=<mx-out.facebook.com>
Dec 12 13:05:57 NOQUEUE: reject: RCPT from outmail024.snc1.tfbnw.net[69.63.178.183]: 554 5.7.1 Service unavailable; Client host [69.63.178.183] blocked using bl.spamcop.net; Blocked - see http://www.spamcop.net/bl.shtml?69.63.178.183; from=<notification+ori=gczf@facebookmail.com> to=<xxx proto=ESMTP helo=<mx-out.facebook.com>
Dec 12 15:35:13 NOQUEUE: reject: RCPT from outmail023.snc1.tfbnw.net[69.63.178.182]: 554 5.7.1 Service unavailable; Client host [69.63.178.182] blocked using bl.spamcop.net; Blocked - see http://www.spamcop.net/bl.shtml?69.63.178.182; from=<notification+h_hj_jwm@facebookmail.com> to=<xxx> proto=ESMTP helo=<mx-out.facebook.com>
Dec 12 19:47:40 NOQUEUE: reject: RCPT from outmail010.snc1.tfbnw.net[69.63.178.169]: 554 5.7.1 Service unavailable; Client host [69.63.178.169] blocked using bl.spamcop.net; Blocked - see http://www.spamcop.net/bl.shtml?69.63.178.169; from=<notification+kr4mmb5xyrkr@facebookmail.com> to=<xxx> proto=ESMTP helo=<mx-out.facebook.com>
Dec 12 21:55:34 NOQUEUE: reject: RCPT from outmail025.snc1.tfbnw.net[69.63.178.184]: 554 5.7.1 Service unavailable; Client host [69.63.178.184] blocked using bl.spamcop.net; Blocked - see http://www.spamcop.net/bl.shtml?69.63.178.184; from=<invite+ooofzz_y@facebookmail.com> to=<xxx> proto=ESMTP helo=<mx-out.facebook.com>

 

So some facebook mail servers really made it up onto spamcop.net.

Good thing is that IPs get removed automatically after a certain time when no ongoing spam activity is reported, so when I checked today, none of these IPs were listed anymore.

The reason people got mails from fb but nevertheless got that error message is simple – facebook uses so many different outmail servers that users hardly notice when a few of them end up being blocked while the vast majority works fine. A single bounce mail should be enough to have facebook display the message though…