$ nc gmail-smtp-in.l.google.com 25
220 mx.google.com ESMTP e10si7339628lfq.412 - gsmtp
HELO lol
250 mx.google.com at your service
MAIL FROM: <hughfguu@gmail.com>
250 2.1.0 OK e10si7339628lfq.412 - gsmtp
RCPT TO: <s................................>
250 2.1.5 OK e10si7339628lfq.412 - gsmtp
DATA
354 Go ahead e10si7339628lfq.412 - gsmtp
From: <fhuigyugy@gmail.com>
To:<se............................>
Subject: lolol
test
.
250 Go ahead
DATA
354 Go ahead. End your data with .
lolololo
.
550 Sorry, we do not accept mail from hosts with dynamic IP or generic DNS PTR-records. Please get a custom reverse DNS name from your ISP for your host 95.153.128.101 or contact abuse@corp.mail.ru in case of error
421 4.3.0 closing connection due to limit reached
А тут вообще ничего не отвечает он