Web mail application is down. The webmail UI in ecloud has been disabled as the team is working on it.
The webmai icon in the ecloud dashboard will not be visible while maintenance is in progress.
There is a new version on the service that is yet to be deployed, which should prevent this from happening. For the time being, the developer will add a cronjob to restart the service daily to prevent this from recurring
Pl note : Normal send / receive of emails using mail clients like Evolution or Thunderbird should be possible.
You can check the current status of the maintenance here.
Hopefully the /e/ team gets it figured out. To be honest, I would like them to use the Mail client in Nextcloud, or at least try to develop their own using that framework.