I'm going to look into how to use tcpdump since you mentioned it. Never tried it before.
To get a clearer view, here's a another run of the command to gmail with the same results.
I've included date before and after, maybe someone can try to time their results to their own email if running 10.1-rel ?
$ date && echo "hi" | mail -v -s "subject"
my.gmail.acct@gmail.com && date
Code:
Sun Jun 21 12:42:04 EDT 2015
my.gmail.acct@gmail.com... Connecting to [127.0.0.1] via relay...
** the usual 5-8 sec delay issue **
220 machine.mydomain.net ESMTP Sendmail 8.14.9/8.14.9; Sun, 21 Jun 2015 12:42:09 -0400 (EDT)
>>> EHLO machine.mydomain.net
250-machine.mydomain.net Hello localhost [127.0.0.1], pleased to meet you
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-8BITMIME
250-SIZE
250-DSN
250-ETRN
250-STARTTLS
250-DELIVERBY
250 HELP
>>> STARTTLS
220 2.0.0 Ready to start TLS
>>> EHLO machine.mydomain.net
250-machine.mydomain.net Hello localhost [127.0.0.1], pleased to meet you
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-8BITMIME
250-SIZE
250-DSN
250-ETRN
250-DELIVERBY
250 HELP
>>> MAIL From:<devuser@machine.mydomain.net> SIZE=44
250 2.1.0 <devuser@machine.mydomain.net>... Sender ok
>>> RCPT To:<my.gmail.acct@gmail.com>
>>> DATA
250 2.1.5 <my.gmail.acct@gmail.com>... Recipient ok
354 Enter mail, end with "." on a line by itself
>>> .
250 2.0.0 t5LGg9KA005899 Message accepted for delivery
my.gmail.acct@gmail.com... Sent (t5LGg9KA005899 Message accepted for delivery)
Closing connection to [127.0.0.1]
>>> QUIT
221 2.0.0 machine.mydomain.net closing connection
Sun Jun 21 12:42:09 EDT 2015