Before you even consider appending, you should read Laura’s post on it (and what happened to one major campaign that appears to have tried it. participate
Yesterday got 5 "notices" from @uscert_gov about "phish" identified by @apwg. Pretty sure that wouldn't come from servers in Europe, though. 3 weeks ago
When I say the message is deferred and is still in the queue, I don't mean that it's bounced and I just don't want to give you the error. 3 weeks ago