Guide
Fibery Email Sync supports threads. We use first element of References header in IMAP response which contain Message-IDs (we take first since it is the id of the first email sent) and set a relation to another Message as Thread field. You can create List View or Table View and group Emails by Threads.
It is useful to sort Emails by Date to have fresh emails on top.
Limitation: Some email clients or servers might not properly set these headers, and forwarded messages can break the thread structure.
Reply via Fibery and maintain email threads
You can Send emails and reply to emails in Fibery.
You should set In-Reply-To: and References: headers in Send Email action to support threads, so you can create a button to reply to emails in Fibery. Check the guide how to do it: Send emails and reply to emails