I remember this being an Ace mod, can someone confirm or deny this? I didn't see that it was updated on Curse, and it's not in the project pages here. I was hoping it would get some loving to be compatible with version 3. The code seems pretty clean. I see it is calling old libraries. I'm not sure if updating those would be enough to bring this back to life.
SendSelf-1.2.1\\sendself.lua:172: AceHook-2.1: Attempt to hook a non-existant function \"SendMailFrame_SendeeAutocomplete\"\nAceAddon-2.0-91091 (Ace2):983: in function <Interface\\AddOns\\Ace2\\AceAddon-2.0\\AceAddon-2.0.lua:976>\n<in C code>: ?\nAceEvent-2.0-91091 (Ace2):260: in function `TriggerEvent'\nAceEvent-2.0-91091 (Ace2):910: in function <Interface\\AddOns\\Ace2\\AceEvent-2.0\\AceEvent-2.0.lua:903>\n\n ---
Someone mention BetterInbox in another thread, but that addon doesn't have any of the functionality from SendSelf. SendSelf allowed me to create an autocomplete whitelist for my alts, so that whever I typed something in the "To:" field, it'd autocomplete the names from the whitelist.