|0||No flags set.|
|1||Message has been read.|
|2||Message has been answered.|
|4||Message is "flagged" for urgent/special attention.|
|8||Message is "deleted" for removal by later Expunge or Close.|
|16||Message has not completed composition (marked as a draft).|
|32||Message is "recently" arrived in this folder. This session is the first session to have been notified about this message; if the session is read-write (the folder was selected with SelectFolder(String) method), subsequent sessions will not see "\Recent" set for this message. If the folder was selected in read-only mode (using ExamineFolder(String) method), "\Recent" flag will not be removed from the message. This flag can not be altered by the client.|
|64||"\*" flag. This special flag may appear only in Imap.PermanentFlags.SystemFlags value. If it's present, it indicates it's possible to create new flags in this folder by attempting to set those flags for messages.|
|128||There are some other (non-system) flags set. The developer may examine AllFlags property of MessageFlagSet object to get the list of all flags set.|
To examine flags of an existing message (or messages), the developer can use DownloadEnvelopes(String, Boolean, EnvelopeParts, Int32) method setting Flags bit in parts parameter value. Then, the developer should iterate through the returned EnvelopeCollection and examine Envelope.Flags property value. This property returns MessageFlagSet object which represents all flags of the message including both system flags and non-standard flags.
To set specific system flags for messages, the developer can use SetMessageFlags(String, Boolean, SystemMessageFlags, MessageFlagAction) method.
See MessageFlagSet topic on more information regarding message flags.