C: A1 CAPABILITY
  S: * CAPABILITY IMAP4rev1 PREVIEW
  S: A1 OK Capability command completed.
  [...a mailbox is SELECTed...]
  C: A2 FETCH 1 (RFC822.SIZE PREVIEW)
  S: * 1 FETCH (RFC822.SIZE 5647 PREVIEW {200}
  S: Lorem ipsum dolor sit amet, consectetur adipiscing elit.
  S: Curabitur aliquam turpis et ante dictum, et pulvinar dui congue.
  S: Maecenas hendrerit, lorem non imperdiet pellentesque, nulla
  S: ligula nullam
  S: )
  S: A2 OK FETCH complete.