=== MailAttributesListToMimeHeaders

Convert attributes of type Collection<String> to headers

Sample configuration:

....
<mailet match="All" class="MailAttributesToMimeHeaders">
  <simplemapping>org.apache.james.attribute1;headerName1</simplemapping>
  <simplemapping>org.apache.james.attribute2;headerName2</simplemapping>
</mailet>
....