This blog post is here to help people like yourself who aren't aware of all of the useful chat commands available in Factorio. It covers private messaging, ignoring players (so that you don't see their messages) and other useful utility commands like /shout so that you can communicate with players not in your team.
Private Messaging
The private messaging commands available in Factorio are:
Sending Private Messages
You can send private messages with the /whisper command. The syntax is /whisper [player name] [message]. Writing the command '/whisper steven44 Hello, this is a private message' would send the message 'Hello, this is a private message' to the user 'steven44'.
Responding to Private Messages
There's no need to write /whisper [player name] every time you want to respond to a message. Typing /r [message] will respond to your most recently received message. So, '/r Hi there' would send the message 'Hi there' to the last player that send you a PM.
Ignoring Players
If a player is being a pest, or you just don't want to see their messages, the /ignore command is what you're looking for. Typing '/ignore steven44' would ignore the player steven44. When a player is ignored you will not see their messages sent in chat and via PM.
To unignore a player, all you need to do is use the command /unignore. This works in the same way that the /ignore command does. '/unignore steven44' would unignore the player with the name 'steven44', meaning you'd see their messages and PMs again.
To see who you currently have ignored, use the /ignores command. Typing '/ignores', will send you a list of all players you currently have ignored. That's all there is to ignoring players. You might also find it helpful to know that you cannot ignore administrators, well, you can, but you will still see their messages.
Other Chat Commands
Shout Command
The shout command can be used to send a message to all players on the server, regardless of whether or not they are on your force. '/shout Hello everyone' would shout the message 'Hello everyone'.
Clear Command
The clear command will clear all messages you have previously received - all you need to do is type '/clear'.
Those are all the commands currently available in Factorio attaining to the chat. If you're an administrator of a server, you may also find our article on moderation commands useful, as it covers muting and unmuting players, as well as clearing messages sent by specific users. If you want to see all available Factorio console commands, see our cheat codes list. If like most other gamers, you use Discord for chat and voice communication, you might also be interested in Discord Help's chat formatting guides that show you how to strikethrough and quote in Discord.