{{- $protocol := "mailto" -}}
{{- $mail := . -}}
{{- $mailWithProtocol := $mail -}}
{{- if strings.HasPrefix $mail $protocol -}}
  {{- $mail = substr $mail 7 -}}
{{- else -}}
  {{- $mailWithProtocol = print $protocol ":" $mail -}}
{{- end -}}
<a
  class="mail obfuscate"
  data-link="{{ range $index := seq (sub (len $mailWithProtocol) 1) 0}}{{ substr $mailWithProtocol $index 1}}{{ end }}"
>{{ range $index := seq (sub (len $mail) 1) 0}}{{ substr $mail $index 1}}{{ end }}</a>