WebTop is working fine with the identiy for email@example.com, also in Thunderbird. The only problem is that there is no French Translation. When I have more time, I will translate it on transifex.com; I registered yesterday and I am waiting for an OK to join the team.
For now, I will follow your suggestion:
I suggest you, if you want to use roundcube, to set a temporarily password and then enter into user page and change identity. Then says to user to reset password.
I will open a new topic to hide “domain” indication.
If you want to continue use roundcube you can easily hide “domain” indication. If you want to do that, please open another topic.
Thank you very much for your help,