well. the only engine that is not inside the bot is fishing, and yes, you put the dll in the Engines folder, if you don't have 1, make it
as for the other plugins, those go into the Plugins folder, and after that you find them under General settings-plugins
for the mail, you mean a macro so the bot can press?...i don't think that works anymore, but you can use the search, r0mbot posted it some pages back
if you mean for yourself, so you can easily mail multiple items (same kind)...i suggest Postal....if you Ctrl+left click an ore for example, it will attach 12 stacks to the mail in 1 click...
ps: if you use postal with the bot, make sure you untick the autocomplete name option in postal, or the bot will screw up and when it will try to mail ...it will fail to delete the name and will try to mail to: NameNameName...and so on

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happy botting