This is not possible at this time. We do have an open feature request on this in addition to some community posts requesting the same though, so this is on our radar!

We did a survey awhile back and an overwhelming majority said they do not like it and many said it was the first feature they turn off in their clients.  For those that have wanted conversations, they have used the native mail clients on MacOS or Window.  Microsoft Outlook on Windows with MAPI will work.  Microsoft Outlook on MacOS with EWS will work.  Most mobile clients using EAS will work.  

Also, in our feature tracking system we have it as a requested feature but it's near the bottom which are requests from customers that have come through various channels.

Hope this helps.

Thanks, Tim. The main complainant is a gmail user, so I'm thinking of having her use POP or IMAP through gmail. That should work, correct?

We asked for it years ago and saw it wasn't coming. I know it's not browser based but anyone that asks for it we push them to emClient which has the functionality. 

Thanks. She's currently reading her email on the iPhone. I'll see what she uses for a laptop.

Just a quick note that this conversation modes are crucial in enterprise company environment like mine. Email thread is too long to be easily confused without conversational view. It works somewhat in Outlook MAPI but it won't work many cases, missing emails in between. I already open a ticket regarding this and escalated to dev team. I mentioned my observation in the email thread, it keeps adding Re: whenever replied and the number of "Re:" keeps growing so that it doesn't show nice conversational view. Hopefully, this will be fixed soon. Thank you.

Hello, 

Thanks for posting to the community everyone. Conversation view is available on Outlook using MAPI/IMAP/POP.

In Outlook while in the mail tab you can click View->Show as Conversation 

Enabling this will make an arrow appear on messages that are conversations. 

Please let me know if this helps. 

Kind Regards,