essentials/Essentials — pull request #659 by JamieSinn (2014-02-17 22:46:41+00:00)
Title: Add mail verification/confirmation in chat

http://www.ecocitycraft.com/forum/threads/suggestion-mail.86067/
Not entirely mandatory to be added, and could be tweaked with a config option.
Here is the original message, from the above link.

"Minecraft Name: AgentHare

Suggestion: To have the command come back with Mail Sent to _________________: *message you sent to them*

Reason: Is very useful for getting solid evidence of you /mail ing a user to get out of your town, or other things. Could be useful for mayors or to make sure you said everything you wanted to.

Link To This Plugin: could be added?"