Almost all messages have Subject fields. Most MUAs include features to display a one-line summary of each message, typically including the value of the Subject field, truncated if necessary. Pine behaves the same way.
Outlook strips all leading whitespace from the original subject.
If the subject contains a colon as the second, third, or fourth character, with no previous space, digit, or colon, Outlook strips everything through the colon, with all subsequent whitespace. Comments No useful semantics in 822. No useful semantics in 822. Used on rare occasions. Encrypted No useful semantics in 822.