Changes from 1.5 include: alterations to the way IMAP fetching works to make it more efficient, particularly with new-only or old-only; a facility to use courier-authlib to fetch user information; delivery to IMAP; removal of from headers, which were a mess; and a number of bugfixes and minor enhancements.
A remove-from-cache delivery action. Command line cache manipulation commands. An envelope-from option for SMTP delivery. Fixes for Google IMAP, proxying over SSL, and some other bugs.
Shell metacharacters are stripped from string tags by default to limit problems with exec/pipe. POP3 may now be fetched over a pipe, like IMAP. fdm can now fetch only new or only old mail for POP3/IMAP. Support for APOP and CRAM-MD5. Some configuration file syntax changes and bugfixes.
Mostly configuration file enhancements and code
cleanup were done since 1.2. ifdef/endif blocks
and inline shell commands are allowed in the
configuration file. A built-in string cache using
TDB was added. Some extra default tags were added.
NNTPS fetching was implemented.
