When creating a new Mailchimp campaign the following error message is displayed:
The Mailchimp campaign was created with the following details:
The cause of this issue was that the "Let users pick plain-text or HTML emails" checkbox in the list settings on the MailChimp website was checked.
This can be seen in the mailchimp.log file:
ERROR [http-apr-9009-exec-2]: 30-Jan-2015 12:19:52.590 Campaign_InvalidContent!
With reference to following Mailchimp KB I followed the steps and this issue is resolved
You need to open Mailchimp website and open the List which is used in CRM, go to List settings and click on “List name & defaults” and uncheck “Let users pick plain-text or HTML emails” Save it and try now.
As per the first part of the error message the Email address should be valid and there should be no Email address in Sender’s name.