The name of the file in new should be "time.MusecPpidVdevIino.host,S=cnt", or "time.MusecPpidVdevIino_unique.host,S=cnt". "dev" is the message's device number, "ino" is the message's inode number (from the previous fstat(2) call); and "cnt" is the message's size, in bytes.
Look for new messages in the new subdirectory. Rename new/filename, as cur/filename:2,info. Here, info represents the state of the message, and it consists of zero or more boolean flags chosen from the following: "D" - this is a 'draft' message, "R" - this message has been replied to, "S" - this message has been viewed (seen), "T" - this message has been marked to be deleted (trashed), but is not yet removed (messages are removed from maildirs simply by deleting their file), "F" - this message has been marked by the user, for some purpose. These flags must be stored in alphabetical order. New messages contain only the :2, suffix, with no flags, indicating that the messages were not seen, replied, marked, or deleted.
- Flag "P" (passed): the user has resent/forwarded/bounced this message to someone else.
- Flag "R" (replied): the user has replied to this message.
- Flag "S" (seen): the user has viewed this message, though perhaps he didn't read all the way through it.
- Flag "T" (trashed): the user has moved this message to the trash; the trash will be emptied by a later user action.
- Flag "D" (draft): the user considers this message a draft; toggled at user discretion.
- Flag "F" (flagged): user-defined flag; toggled at user discretion.
查看邮件后，文件名变成 1465266566.M802559P62166.localhost.localdomain,S=3683,W=3762:2,S 回复该邮件后，文件名变成 1465266566.M802559P62166.localhost.localdomain,S=3683,W=3762:2,RS 保存到草稿箱，文件名变成 1465267912.M313889P61446.localhost.localdomain,S=1356,W=1392:2,DS