Hi AdeotiD ,
I am an engineer that is working on the Shopify integration for Constant Contact and one of the features of our integrations is to automatically sync any email address, with permission to send, to your Constant Contact account whenever there is a new address added to Shopify.
I looked into why your email addresses were not syncing and it appears that you are using a MailChimp signup form on your website so the contacts are going directly into MailChimp instead of into your Shopify database. If the contacts are not making it to your Shopify database we do not have access to them.
You can resolve this by switching to native Shopify Signup form or using the Constant Contact signup forms.
Please let me know if you have any questions.
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