{{- $author := index .Site.Data.authors ((or .Params.author .Site.Author.default.user) | default "default") -}}
{{- $source := print $author.user "/messages/" .File.LogicalName -}}
{{- $source = replace $source "/" "-" -}}
{{ if .ExpiryDate }}
  {{- $source = md5 $source -}}
{{ end }}
{{- $source -}}