Hello user356733 ,
Thank you for reaching out to Constant Contact API Developer Support. My team is here to assist outside software developers with questions about building into Constant Contact's API.
Due to limited bandwidth and the complexity of API related inquiries, Constant Contact’s API Developer Support team is only able to provide support via email at this time, but we’re happy to answer any questions that pertain to Constant Contact’s API endpoints and functionality.
Constant Contact is not set up to send email directly via SMTP. We balance the sending of emails in a way that does not allow for this approach. Basically, we have far more than one mail server, and we can't directly access any of them through a username and password. Our system is designed for you to create email campaigns using our templates or your own HTML code, but they are sent from our server and authenticated as such.
Please have a look and let us know if you have any other questions! You can contact the API Developer Support team directly by emailing us at firstname.lastname@example.org and referencing case #29724903.
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