Would it be possible to implement an option for Postbox style threads? I.e. in the mailbox list view, messages are grouped together if 1. they're in that mailbox only, 2. they're linked to each other using the Message-ID: / In-Reply-To: headers, and 3. Subject: lines are ignored.

(Or even better, implement thunderbird/mutt style threads, which recreates the actual thread hierarchy, which makes following mailing lists so much easier - can I dream??)

With Conversations on eM Client, I currently have one conversation in my inbox with 389 emails, linked together because the subject line is empty. I.e. every single email in my archive I've ever sent or received with a blank subject is now in a linear conversation group in my inbox.

Similarly, I have another 37 emails with subject "Ryanair Travel Itinerary" which I need to keep archived for several years for accounting reasons. Nothing to do with Ryanair, but I filed those emails into other mailboxes specifically to get them out of my hair and I don't ever want to see them again unless there's a need to look them up explicitly.

The current options for dealing with this are: disable conversations completely, which stops all grouping of linked emails, which is no use at all. Alternatively, conversations can be configured for message view only, which moves the problem to the message viewing panel: I received another email with no subject line again yesterday, and now the message view prompts me with "<no subject>" and "Show 388 older emails". This isn't a viable approach to message categorisation from the UX point of view.

There are a lot of forum postings about this issue, including a recent discussion which explains the underlying issues in more detail:

https://forum.emclient.com/t/how-does-em-client-implement-threading-to-construct-a-conversation/100711

But for me, the current conversations/threads implementation on eM Client is a show-stopper regression over Postbox.