When you resolve a conversation you are saying "I think this is sorted". Auto-close is what happens next, and it exists because you might be wrong.

Why resolved and closed are different

Resolved: You have answered and believe it is finished. The customer may disagree.
Closed: Finished and filed away.

The gap between them is the window in which the customer can say "actually, that didn't work". Auto-close is what turns the first into the second once that window has passed.

What auto-close does

It closes resolved threads automatically after a delay you choose. Nothing else changes. No message is sent, and the customer is not told.

Without it, resolved threads accumulate forever and somebody eventually has to close them by hand. With it, a conversation you resolved on Monday quietly closes itself on Wednesday, and your workspace stays tidy without anyone doing tidying.

How to change the delay

1Click Settings at the bottom of the left-hand sidebar.
2Open Threads, then Threads.
3Find the Auto-Close section.
4Use the Close resolved threads after dropdown to pick a delay.

The default is 48 hours, which suits most teams.

What happens if the customer replies

They reopen the conversation. A reply to a resolved thread puts it back to Open and back in your inbox, in the same thread, with all the history intact.

You will see the same rule from your side. Replying in a resolved thread shows a line above the composer saying that sending a message will reopen it.

This is why the delay matters. Set it too short and a customer coming back the next morning starts from a closed conversation; set it sensibly and they continue the one they were already having.

Choosing a delay

24 hours or less: Fast-moving, high-volume support where questions are simple and customers rarely return. Keeps things tidy, at the cost of the occasional reopened conversation.
48 hours: The default, and right for most teams. Covers somebody who reads your reply the next working day.
Longer: Worth it if your customers are businesses. A reply sent on Friday afternoon may not be read until Monday, and a weekend inside the window is worth having.

Match the delay to how quickly your customers read email, not to how quickly your team works. Those are different numbers, and it is the first one that matters here.

What auto-close does not do

It does not resolve anything. Only a person or an explicit action moves a thread to resolved. Auto-close acts only on threads already there.
It does not delete anything. Closed conversations are still searchable and still attached to the customer.
It does not stop customers reaching you. A reply arrives whether or not the thread has closed.
It does not affect timers. The resolution target was already met when you resolved it.

How auto-close works for resolved threads