The SELECT and EXAMINE Commands

When either the SELECT or EXAMINE command is successfully issued, the server will return to the client a set of useful information about the mailbox, which can be used to guide commands issued from the Selected state. This information includes the following three mandatory responses:

• <n> EXISTS: Tells the client the number of messages in the mailbox.
  
  
• <n> RECENT: Tells the client the number of recently-arrived (new) messages.
  
  
• FLAGS (<flag-list>): Tells the client which flags are supported in the mailbox. These include the following: “\Seen”, “\Answered”, “\Flagged” (marked for special attention), “\Deleted”, “\Draft” and “\Recent”. (The backslashes are part of the flag names.)

The reply from the server may also contain these optional replies:

• UNSEEN <n>: The message number of the first unseen message.
  
  
• PERMANENTFLAGS (<flag-list>): A list of flags (as for the FLAGS response above) that the client is allowed to change.
  
  
• UIDNEXT <n>: The next unique identifier value. This is used to check for changes made to the mailbox since the client last accessed it.
  
  
• UIDVALIDITY <n>: The unique identifier validity value, used to confirm valid UID values.