[Users] How to filter utf8 messages

[Pierre Fortin]

Hi,

Is it possible to filter messages containing:

From: =?utf-8?B?5paw5b...
Subject: =?utf-8?B?44CM44GI4...

with something like this:
enabled rulename "UTF8"
   subject matchcase "=?utf-8?" &
   from matchcase "=?utf-8?"
   move "#mh/Mailbox/inbox/SPAM"

I tried and it doesn't match -- filtering log:
 Subject: header value [ 「えきねっと」アカウントの自動退会処理について ]
 does NOT contain [ =?utf-8? ] (Case insensitive)

Actually, the raw message as seen with View>Message Source does contain
"=?utf-8?"...

Thanks,
Pierre