[2.3.0] Checkmk Werk 16375 created: Rule "Check Email": Allow all makros

[//]: # (werk v2) # Rule "Check Email": Allow all makros key | value ---------- | --- date | 2024-01-15T13:59:03+00:00 version | 2.3.0b1 class | fix edition | cre component | checks level | 1 compatible | yes The ruleset "Check Email" recently featured stricter validation. As a result, no makros (like `$HOSTNAME$`) could be used anymore. This was partially compensated for in [#15203](https://checkmk.com/werk/15203), but this was still too restrictive. Users can now configure validated host adresses or unvalidated strings containing macros.