Infusion soft contacts API

I want to know how can I access custom fields in contacts API for getting the smtp details.

I am unclear of what you are asking. What SMTP details. Are you referring to? Are these custom fields that you have added? If so are you using the REST or the XML/RPC API?

Actually we are using Rest API of Infusion soft for listing the contact of investors and we want to get smtp details of each investors in contacts API I already checked on smtp fields in custom fields but API is not returning smtp fields. So kindly guide me how can we access.

Can you give me an example of what you mean by SMTP fields? Do you mean email addresses?

Here is an example, Can you please tell us it is possible or not, Actually we want to retrieve these selected custom fields, if it is possible so kindly guide us how can I access them. Thank you.

And we are using this endpoint but custom fields are not returning in json.

But when we call retrieve contact API that’s return custom_fields array with id and contact but my selected custom fields are not returning.

Here is the screenshot.