[exim] Control=freeze in acl_smtp_mime

Hi List,

With the release of Exim 4.50 the command control=freeze is no longer
allowed in the acl_smtp_mime acl checks. It does however work in Exim 4.43.
There is nothing in the CHANGELOG indicating this change. Any specific
reason as to why this is not allowed in the latest version?

Cheers,

Andre