$ telnet 192.168.195.201 25
Trying 192.168.195.201...
Connected to 192.168.195.201
Escape character is '^]'.
220 myhost ESMTP Sendmail 8.9.3
250 myhost Hello [192.168.195.15], pleased to meet you
550 5.1.1 test2... User unknown
550 5.1.1 admin... User unknown
250 2.1.5 heho... Recipient ok