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When I try a Nmap scan it shows that all ports all filtered, but how does this domain ( aspmx.l.google.com ) suppose handle all the mails if all ports are closed, when using Google Apps for businesses?

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closed as too localized by Jeff Ferland, EEAA, Shane Madden, Ward, mgorven Jun 25 '12 at 2:38

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1 Answer 1

$ telnet aspmx.l.google.com 25
Trying 173.194.67.26...
Connected to aspmx.l.google.com.
Escape character is '^]'.
220 mx.google.com ESMTP z8si11438427wix.13

Port 25 is open to receive email via SMTP.

Your nmap result is wrong and you should be aware of the legalities of port scanning since it's a grey area in some places. Potentially, Googled detected it, and blocked you.

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Only port 25 is open? What about POP? –  user1095332 Jun 24 '12 at 19:05
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aspmx.l.google.com is designated for inbound mail only - that's why it's used in MX records (for other servers to push emails through to). Use pop.gmail.com (POP/IMAP) or smtp.gmail.com (SMTP) if you're configuring your clients so they can retrieve it. –  Jay Jun 24 '12 at 19:09
    
Ok, so it would not be any problem if I would use my own (non-Google and non-Postini) server for the primary MX record (priority =1) and only forward port 25 to aspmx.l.google.com? –  user1095332 Jun 24 '12 at 19:31
    
I can't imagine it'd be a wise idea to be honest: all inbound emails will now have their source IP as your server, which may cause SPF records to bounce: en.wikipedia.org/wiki/Sender_Policy_Framework. This would leave an awful lot of emails in your spam box. –  Jay Jun 24 '12 at 19:49
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@JayShah, having an inbound gateway is supported, but for the best add some settings in your Google Apps control panel. support.google.com/a/bin/answer.py?hl=en&answer=60730 –  Zoredache Jun 25 '12 at 6:17

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