이 함수는 주어진 sequence일련번호에 대한 헤더를 페치하고, 전체 정보를 돌려준다. sequence값은 flags가 FT_UID를 갖는다면 UID나 메시지 인덱스(indices)의 일련번호(sequence)가 된다. 돌려받는 값은 메시지 헤더의 각각을 서술하는 다음과 같은 속성을 갖는 객체의 배열이다:
subject - the messages subject
from - who sent it
date - when was it sent
message_id - Message-ID
references - is a reference to this message id
size - size in bytes
uid - UID the message has in the mailbox
msgno - message sequence number in the maibox
recent - this message is flagged as recent
flagged - this message is flagged
answered - this message is flagged as answered
deleted - this message is flagged for deletion
seen - this message is flagged as already read
draft - this message is flagged as being a draft