Can't add rules for domains that contain "--"

I’m trying to add a new block in the email filter (Email -> Filter -> Rules by Email Address), specifically my domain is something like first–
WebUI doesn’t accept this kind of domain even if double hyphen is correctly supported and permitted.

This is the error

For now, I forced it by CLI and it works pretty well.

config setprop amavisd SenderBlackList
signal-event nethserver-mail-filter-save