Your question
In 0.15 there is a option for the master-user but there is no such information on how to migrate (that I could find) to the 0.16 version. How is this now solved?
This has good confirmation. Let me answer.
The master-user setting was replaced by an impersonate permission model.
Instead of a dedicated master-user config, grant the impersonate permission to a regular account (typically via a Role). Any account holding that permission can log in on behalf of another account using a composite login of the form <target>%<impersonator>, authenticating with the impersonator’s own password.
For example, if [email protected] has the impersonate permission and you want to access [email protected]’s mailbox, log in as [email protected]%[email protected] using [email protected]’s password. This works the same way for single-label account names on setups not using user@domain logins. Since this grants broad access, assign the impersonate permission sparingly.
See: Administrators | Stalwart
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