Thanks a lot for using our service. Sorry for the inconveniences, the issue will be resolved in one of the next versions.
Now you can to make the following: add the line <add key="core.notify.tariff" value="false" /> to the file /var/www/onlyoffice/WebStudio/web.appsettings.config (in container with Community Server if you use Docker version) It will help you avoid this type of notifications. It is recommended to restart service monoserve after changing the config-file.
You also can customize the type of notification letters in source code: public void SendTariffWarnings(DateTime scheduleDate) in web\studio\ASC.Web.Studio\Core\Notify\StudioNotifyService.cs For example look for lines: #region 3 days after registration #endregion #region 7 days after registration