jdMorgan - 11:51 pm on Feb 11, 2010 (gmt 0)
The first thing I ask in these cases is, "Did you verify that every old-domain URL invokes a single 301-Moved Permanently" redirect to the correct new-domain URL using a tool such as the 'Live HTTP Headers' add-on for Firefox/Mozilla browsers or a similar tool with which you are familiar and which you trust to show all the details of the client-server transaction?"
If the answer is "No" or "No, but I saw it redirect in my browser," then I suggest using a server headers checker as described. HTTP protocol is a technical thing, and you have to get it right.
If the answer is "Yes, the headers checker shows a single 301-Moved Permanently" redirect response from the server, and the Location header sends me straight to the correct page," then ignore this and accept my apologies for posting. But I've seen far too many sites damaged by what appears to be a correct redirect implementation, but in fact is incorrect (such as a 302-Found) and is therefore returning a different status response, and giving unwanted signals to the 'bots. So I actually look at posts like this with an eye to how strong the 'redirect status verification' testing of the redirects is claimed to be.
I figure the more frequently a site is spidered and the more it is 'trusted,' the more shallow the traffic drop will be and the sooner rankings and traffic will recover -- assuming that the HTTP protocol signaling is correct.