822date.1 - indimail/indimail-mta GitHub Wiki
822date - print the date in a mail message
822date [ name ]
822date reads an 822-format mail message from its standard input, and prints the 822-format date shown in the last header field named name, or Date if name is not supplied.
822date prints the date in three forms: first, ISO format, using the time zone shown in the field; second, ISO format, using UTC; third, ctime format, using the local time zone. Beware that most ctime libraries do not correctly handle leap seconds or years past 2037.
822field(1), 822received(1), ctime(3)