MailChimp Spam is on the rise and it is probably about to get much worse.
Since the beginning MailChimp was a trusted mail service because they had a rule in place - you had to "Double Opt In" to sign up for a subscription to any of their client's lists. This means you signed up and were then sent an email asking you to confirm that it was you and that you want to be in the list. This is the way it should be - otherwise anyone who knows your email address could sign you up for a few hundred lists and your email box is about to suffer the consequences.
MailChimp has now removed the "double opt in" requirement and is allowing anyone to sign other people up for their lists. For some professional Spammers who have access to harvested email lists this is a total opening of the internet to allow them to do their trade.
Due to this recent change in their policy - we are now marking all email that pass through our TeleSites.net Spam Filters from MailChimp with an appended subject line that reads: [SPAM?-MailChimp]
If you'd like to stop getting email from any specific MailChimp list the only option you have is to use the unsubscribe link at the bottom of the email. At least they haven't decided to do away with that - yet.