KMail is a plugin that allows text messages to be sent to other player, regardless of whether they are online. Messages can also be sent between servers. It is inspired by real-life e-mail and by turt2live's xMail plugin.
Usage
To send a message to a player named "bob":
/kmail send bob Hello there!
To read an unread message:
/kmail read
To list all messages in your mailbox:
/kmail list
To list unread messages (i.e. messages with the tag "unread"):
/kmail list t:unread
Commands
/kmail help [topic] - View help
/kmail send <address> [message] - Send a message
/kmail list [criteria] [page] - List messages (optionally refined by search criteria)
/kmail select <id> - Select a message to be acted upon
/kmail read [id] - Reads either the selected message or one specified by its ID and marks it as read
/kmail read next - Reads the first unread message and marks it as read
/kmail tag [id] <tags...> - Add tags to a message
/kmail untag [id] <tags...> - Remove tags from a message
For full command help, refer to the in-game help system (via the /kmail help command).
Permissions
kmail.help - Gives access to view the builtin help (/kmail help)
kmail.send - Gives access to send mail (/kmail send)
kmail.send.remote - Gives access to send mail to remote servers
kmail.send.all - Gives access to send mail to all players on a server (should be given to responsible players only to prevent abuse)
kmail.list - Gives access to list and search mail
kmail.select - Gives access to select messages
kmail.read - Gives access to read mail
kmail.tag - Gives access to tag and untag messages
Source code
The plugin's source code can be found on its Github repository.