[@ ...] label

For keeping emails "from" or "belonging to" certain source.
There is a blank between '@' and source name to support typing look-up in Move or Label command.  So it becomes dash in search expression: "label:@-...".

Examples

• users  =  user's incidents & requests
• helpdesk/support  =  helpdesk/support team's references
• corporate, vendors, management
• org.etc = miscellaneous from various departments

Also another label using same symbol: "@?" = somethings or some other things (depending on individual strategy) from Internet.  The symbol reflects Internet email-address notation (name@somewhere.com).