I believe Mother's Mail
was where the feature originated; since then, Seagoat's Mail
, Fetish, DrumsUI and ProfitUI all have duplicates of the feature. If you don't use any of those UIs and you only want the forwarding feature, you can drop the eq2ui_mainhud_openedmail.xml
file from the Seagoat package into your custom UI folder. But I will caution you that it suffers from the general snipping/trimming/juggling of UI elements that was common ten years ago.
Below is the current default window with forwarding added.