Hello @lmoffat. I apologize for any confusion. Any emails that appear in your archive (including those created before March 2013) will still be visible in your archive. As it states in the email, your archive link will remain active until February 28th, 2017. If you would like, you can check out how to use the new embeddable archive here.
When you are brought over to our new user experience, email and survey campaigns and their reporting created before March 2013 will be removed from your account. If you needed any reporting, you would need to export this information. Also, if you did want copies of these emails, you would either copy the email to create a draft or download the email as a PDF. I would suggest if you did need to copy any of those pre-March 2013 emails, put the drafts into a folder so you'll know where to locate them.
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