What is a comment backfill?

Most comment-to-DM tools only count from the moment you save the automation. Every fan who commented earlier is left waiting. That hurts most when a Reel takes off before your automation is live: hundreds of people asked for the link and none of them got it. A backfill fixes that by scanning the post's existing comments and treating each match like a new one.

The limit is Meta's. A professional account may send one private reply per comment, within 7 days of that comment. So a backfill can DM anyone who commented in the last 7 days, but for older comments the only answer left is a public reply. Picking an old post is not the same thing: that only catches new comments on it from now on.

A good backfill is paced. Sending hundreds of DMs in a minute looks like spam, even when every fan asked. It also never messages the same fan twice.

In theZio, open an automation's Advanced settings and choose which comments it should answer: the last 24 hours plus new ones on every plan, or all old comments plus new ones on Pro. Comments older than 7 days get your public reply only, so keep one switched on. Read how to reply to old Instagram comments, what a private reply is, or the old comments feature.