speed improvements: connection failure history (inter-process) even MX-preference selection by history connection caching (inter-transaction, inter-process) parallelization of getting MX and SMTP option q: quick start daemonize address sorting (on over 100 recipients) when default relay is defined operational: AAAA query cay be ignored? if ANY query contains MX and A, or if additional answer for MX query contains A. TCP DNS query return information about issued SMTP command on error condition (LMTP data response) changing envelope-from par recipient for errornous destination distinction (like "qmail") configuration of alias names for the host (refering $=w of sendmail.cf) IPv4/v6 address ordering par domain protocol (known bugs): 8bitMIME management DSN notification... reliability: checkpointing configure: static link required?