On a newly-installed mail server with the IP address 10.10.10.1, ONLY local networks
should be able to send email. How can the configuration be tested, using telnet, from
outside the local network?

A.
telnet 10.10.10.1 25 MAIL FROM<admin@example.com> RECEIPT
TO:<someone@example.org>

B.
telnet 10.10.10.1 25 RCPT FROM:admin@example.com MAIL
TO:<someone@example.org>

C.
telnet 10.10.10.1 25 HELLO bogus.example.com MAIL FROM:<anyone@example.org>
RCPT TO:<someone@example.net>

D.
telnet 10.10.10.1 25 HELO bogus.example.com MAIL FROM:<anyone@example.org>
RCPT TO:<someone@example.net>

E.
telnet 10.10.10.1 25 HELO: bogus.example.com RCPT FROM:<anyone@example.org>
MAIL TO:<someone@example.net>