define local $\ and $_ in &sendmail to protect us from outside settings (is this really needed?)
delete $mail{Sender} used for envelope sender, but not needed as header
internal rewrite using subs to send and receive on socket
Changes for version 0.78_2
fix old bug with dot as 77th char (check this!).
correct very old bug where port number was not extracted from stuff like 'my.server:2525'.
fix time_to_date bug with negative half-hour zones (only Newfoundland?)
use Sys::Hostname to get the hostname for HELO. (I think it has been part of the standard distribution for many years now)
support different envelope sender through $mail{Sender}
Remove old configuration variables from version 0.74.
Change case of headers: first character after "-" also uppercased now, so people who believe this is required because Outlook does it this way stop complaining. :-)