I think it belong to your email content and sender. Not from mailchimp side.

my auto responder also seems to go to the "promotions" area on gmail

Google created the promotions tab and the social tab to help separate and organise email for its users. This has been bounded around for a while as it can affect open rates.

My understanding is that emails will end up in the promotions tab based on the content of the email as davidpham has said.

You can try and follow some rules to help make your emails less promotional - but don't forget not everyone reads their Gmail from the web based email client. So in the case they are bringing their email to their computer through a native client they will all appear in one list. Unless the user has setup their own rules of course!

You could try the following to help keep emails out of the promotions folder

- Keep to one link in your email - you may have to test this as more than one link in a long email is going to help CTR so you may have to weigh this up carefully

- Don't include pictures

- Use the subscribers name if you can using merge tags

- Try not to use too much promotional copy and write like you are talking to the subscriber or like he is your friend.

- Use letter form - i.e


Dear Fred,

Email message

Regards

John

Having said all this many of these items (such as using pictures) can help open rates and click through rates.. so you really have to test and see what works for you. It might not necessarily be a bad thing you are landing in the promo folder.

Also - don't chase down trying to cheat Google's algorithms.. you will go mad trying to keep up and could be just focusing on delivering good quality content

HTH