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What happens when trying to add contact who unsubscribed


What happens when trying to add contact who unsubscribed

Can you confirm what happens if our system (using the api) tries to add a contact to a new list in Constant Contact but that contact already exists and his email address is marked unsubscribed? 


1) Does this result in a non-fatal error?

2) This apparently will not add the contact to the new list. Please confirm.






Hello Ken,


When you attempt to add a contact who is unsubscribed, the outcome depends on the API call you are using. Here are the details:


Bulk Import Contacts API:

  • The contacts that are unsubscribed will not be added to any lists.
  • The bulk import will continue and import any contacts that are not unsubscribed.


Individual Contact APIs:

  • The individual contact APIs feature a URL parameter called action_by that has two possible values: ACTION_BY_OWNER and ACTION_BY_VISITOR
  • When using ACTION_BY_OWNER you are not permitted to add an unsubscribed contact to any lists, and any attempts will result in a 400 error response from the API that will include a message explaining why the action cannot be completed.
  • When using ACTION_BY_VISITOR you are permitted to add unsubscribed contacts to lists and re-subscribe them. This is specifically because this option is only meant to be used in a scenario where the contact(visitor) is initiating the action. An ideal example is a sign-up form.

If you have any questions for me, please let me know!



Elijah G.
API Support Engineer
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