Thanks to the emergence of global trade and regular shipping routes it has become possible for a centralised mail system. In most settlements and villages of the civilised world you can find mailboxes.
When a player locates a mailbox he may double click it to access a popup mail GUI. This allows a player to review his/her previous mail and send new email to a recipient by name.
Mailboxes are only found in the civilised world and where the Tsiyon forces have established settlements. However, players may purchase a blueprint for a mailbox for their city at a cost.