Are you talking about custom actions here? Direct Mail is a channel within AJO campaign and has an Action ID that can be used for future audience segmentation or CJA analysis. Or are you talking about "reaction" or engagement signals from these channels?

Send Time Optimization, as well as additional recurring schedule options will be coming to AJO Campaigns as part of our roadmap for next year. 

You would have to add to an existing profile attribute field. This would be a concat of upstream values in a journey if needed. Additionally, there is an ability to create Computed Attributes. https://experienceleague.adobe.com/en/docs/experience-platform/profile/computed-attributes/overview

You're approach above seems feasible. If you are looking at a downstream Direct Mail service, you can use the Direct Mail action inside of AJO Campaigns to export a .txt or .csv file to S3, or FTP path. This action gives you the ability to select an audience and the columns of data along with any da...

Have some thoughts and questions - will follow up with you. 

No relationship required. Dataset does not need to be enabled for profile. 

Can you DM me with further details on how you are replacing the data in the dataset? 

In addition to the example JSON values from @Mohan_Dugganab  - would suggest creating the subscription lists from within AJO ahead of import and trying to match the naming as close as possible. The subscription list added within AJO will give you a nice reporting system to better understand subs/uns...

HI @arpan-garg -Couple of questions.  1) Does your schema have "addressID" set as the primary identity? 2) Do you have unique "addressID" for each row in the dataset? 3) When you used the API call to enable your dataset for lookup did you get a Success 200 message returned? 4) When using the functio...

@arpan-garg Do you see it as more useful to add a throttle rate at the channel configuration level (meaning each time a push is invoked it is throttled at the same rate) or would your priority be to add this at the instance level for a Campaign/Journey. I think it may depend on which persona would u...