Snooze function is not working with United Domain mail accounts

Dear eM Client Team, Dear Use

We are currently migrating all our email accounts from DomainFactory to United Domains. During this transition, we’ve encountered a recurring issue with all newly created accounts on United Domains when used with eM Client:

The Snooze function no longer works correctly. When an email is snoozed, it briefly appears in the Snoozed folder and then immediately returns to the Inbox — as if eM Client marks it temporarily, but the change is not retained due to a synchronization issue. This problem does NOT occur with accounts hosted by other providers such as DomainFactory.

We’ve already performed a complete clean reinstallation of eM Client (including registry cleanup via Revo Uninstaller), but the issue persists.

Our questions:

  1. Are you aware of any known issues between eM Client and United Domains regarding the Snooze function?
  2. Could this be caused by something specific on the mail server side?
  3. Are there any particular IMAP settings or adjustments required when using eM Client with United Domains?

We’d really appreciate your insights and any suggestions that might help resolve this.