imap.md

Metadata about each folder is stored in .imap files.

The current version (version 3), looks like this:

{
  "version": 3,
  "uid_validity": 1606316666,
  "messages": [
    {
      "uid": 1,
      "offset": 0,
      "length": 3736,
      "flags": ["Draft"]
    }
  ]
}

• version - the file format version,
• uid_validity - the UIDVALIDITY attribute for the folder on the IMAP server,
• messages - metadata about the downloaded messages,
• uid - the message's unique identifier,
• offset - the offset of the start of the message in the accompanying .mbox file,
• length - the length of the serialized message,
• flags - any of the standard flags which were set in the message when last downloaded.