Code:[203.0.113.2] The IP you're using to send mail is not authorized to 550-5.7.1 send email directly to our servers. Please use the SMTP relay at your 550-5.7.1 service provider instead. Learn more at 550 5.7.1 [URL]https://support.google.com/mail/?p=NotAuthorizedError[/URL] h1si7104782plt.44 - gsmtp (in reply to end of DATA command))
So it's your ISP that told Gmail to refuse email from your IP. My ISP has clearly not done this:In order to prevent spam, Gmail refuses mail from IP addresses that are not authorized to send mail. The determination of whether or not an IP address is authorized to send mail is made by the ISP that provides you with the IP address. This list typically contains consumer IP ranges offered for dialup, DSL, or other broadband access.
Code:
dice@maelcum:~ % nc alt1.gmail-smtp-in.l.google.com 25
220 mx.google.com ESMTP t18si6888565pgh.89 - gsmtp
EHLO sirdice.nl
250-mx.google.com at your service, [2001:XXXX:XXXX:XXXX::1]
250-SIZE 157286400
250-8BITMIME
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
MAIL FROM: <admin@sirdice.nl>
250 2.1.0 OK t18si6888565pgh.89 - gsmtp
RCPT TO: <sirdice@gmail.com>
250 2.1.5 OK t18si6888565pgh.89 - gsmtp
DATA
354 Go ahead t18si6888565pgh.89 - gsmtp
subject: some test
hello world