Magic header detection for emails starting with an ARC- signature header, and for the 2+ header cases also allow Received as a matching header
<match value="\nFrom:" type="stringignorecase" offset="0:8192"/>
<match value="\nTo:" type="stringignorecase" offset="0:8192"/>
<match value="\nSubject:" type="string" offset="0:8192"/>
+ <match value="\nReceived:" type="string" offset="0:8192"/>
<match value="\nMIME-Version:" type="stringignorecase" offset="0:8192"/>
</match>
<match value="DKIM-" type="string" offset="0">
<match value="\nFrom:" type="stringignorecase" offset="0:8192"/>
<match value="\nTo:" type="stringignorecase" offset="0:8192"/>
<match value="\nSubject:" type="string" offset="0:8192"/>
+ <match value="\nReceived:" type="string" offset="0:8192"/>
+ <match value="\nMIME-Version:" type="stringignorecase" offset="0:8192"/>
+ </match>
+ <match value="ARC-" type="string" offset="0">
+ <match value="\nMessage-ID:" type="string" offset="0:8192"/>
+ <match value="\nFrom:" type="stringignorecase" offset="0:8192"/>
+ <match value="\nTo:" type="stringignorecase" offset="0:8192"/>
+ <match value="\nSubject:" type="string" offset="0:8192"/>
+ <match value="\nReceived:" type="string" offset="0:8192"/>
<match value="\nMIME-Version:" type="stringignorecase" offset="0:8192"/>
</match>
</magic>
