A follow-up stage can send as a reply on the email you already sent that recipient. In their inbox it lands under the original message, with the subject Re: your original subject, exactly the way a person following up by hand would send it. The alternative is a separate email with its own subject line, which starts a new conversation. You choose this per stage, so a sequence can mix both.

1. Open your campaign and go to the Sequence step.
2. Turn on Automated Follow-ups if it is not on already, and add a stage.
3. Expand the stage card and find the Conversation dropdown.
4. Choose Reply in thread or Start a new thread.

The stage card tells you what it will do in three places. The line under the dropdown explains the current choice. The collapsed stage header reads Replies in thread or New thread, so you can see the whole sequence at a glance without expanding anything. And the summary sentence at the bottom of the expanded card spells out the send in full, ending with either “It replies on the original email, so recipients see Re: your original subject” or “It sends as a separate email with its own subject line”.

When a stage is set to reply in thread, the field that is normally Subject line is relabelled Internal label, and its placeholder changes to Name this stage for your team. Below it, the hint reads “Recipients see Re: your original subject. This label is only visible to your team.” Use the label to say what the stage is, for example Nudge after one week. It appears in the composer and in campaign reporting, never in the email.

The Copy from original shortcut above the field still works on a threaded stage: it fills the field with Re: your original subject and copies the original body into the stage. On a threaded stage that filled-in text is a label, so rename it to something your team will recognise.

• A stage you add in the composer starts on Reply in thread. Change it on the stage before you send if you want a fresh conversation.
• A campaign created from a campaign template starts every stage on Start a new thread. A template carries a written subject line for each stage, and threading would turn that authored line into an invisible label, so the template’s subject is kept instead. You can switch any stage to reply in thread afterwards.
• A stage on an existing campaign keeps whatever it was saved with. Campaigns built before this option existed read as Start a new thread, so nothing about an in-flight sequence changes on its own.

Threading is anchored to the first email of the campaign. If stage 1 starts a new thread and stage 2 replies in thread, stage 2 lands back on the original conversation, not on the one stage 1 started. The composer says so on the stage itself: when an earlier stage starts a new thread, the threaded stage shows “An earlier stage starts a new thread. This reply still rejoins the original conversation, not that new one.”

The reply subject is built from the subject that recipient actually received, so personalized subject lines stay correct per person. If the original subject already began with Re:, it is not repeated, so nobody receives Re: Re:.

Open a campaign and look at the Follow-ups card. A threaded stage adds Replies in thread to its timing line, and a second line reads “Internal label. Recipients see Re: your original subject.” That way the stage name in reporting is never mistaken for the subject line that went out.

• Choose Reply in thread when the follow-up is a nudge on the same topic. It carries the earlier message with it, so the recipient has the context in front of them.
• Choose Start a new thread when the stage makes a genuinely different offer, or when the subject line is doing the work and you want to test it. A threaded stage cannot show a subject line of its own.
• Choose Start a new thread for a long sequence where the original message is weeks old, so the last stage does not arrive buried under a conversation the recipient has stopped opening.
• Mixing both is fine. Threading is decided per stage, and a later threaded stage always returns to the original conversation.