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 "From name" was an email address but it should have been just a name.
This can be seen in the mailchimp.log file:
ERROR [http-apr-9009-exec-2]: 30-Jan-2015 12:19:52.589 Mailchimp Error code 311[Campaign_InvalidContent], from_name - Please do not use an email address
ERROR [http-apr-9009-exec-2]: 30-Jan-2015 12:19:52.590 Campaign_InvalidContent!
In Sage CRM 7.3c a better error message has been introduced: