telnetSMTP
telnet mail.example.com 25 Trying 1.2.142.8... Connected to mail.example.com. Escape character is '^]'. 220 ubuntu-2gb-hel1-2 ESMTP Exim 4.86_2 Mon, 21 May 2018 06:35:42 +0200
telnet mail.example.com 25 Trying 1.2.142.8... Connected to mail.example.com. Escape character is '^]'. 220 ubuntu-2gb-hel1-2 ESMTP Exim 4.86_2 Mon, 21 May 2018 06:35:42 +0200