I've had a custom built website for 5 years which, prior to Zoho, would send marketing emails automatically based on certain criteria. For example, if user bought product A but a month since related product B has come out they have not purchased that then it would send a targeted email saying "hey, you bought A, do you also want to buy B?". As far as I can tell, Zoho does not have any API to achieve this programmatically (eg call Zoho API to send a list of users an email with this content). Have I missed anything?

So if I want to achieve this, I would need my website to produce a pre-filtered contact list in CSV format, import that into Zoho by the user interface, set up the email template, and then initiate the sending of that, correct?

Thanks.