It's possible the fellas at Cloud City have been browsing through the Member Lists here, or at GH or Rs, and adding any of the publicly listed e-mails to their mailing list...
That'd be my guess anyway. Some good deals to be found at their store from time to time though, so it may be worth a quick looksee through their e-mail sales and specials. Definitely a great vintage offering at CC to be sure. But if you guys ain't interested, there's always the ol' "UNSUBSCRIBE" option.

EDIT: Looks like Brent's e-mail isn't publicly displayed here or at GH, but Jamie's is at both places. But they're both displayed in the User List over at RS, so maybe that's where they're getting it from...