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From: cronfy <cronfy@gmail.com>
Date: Mon, 2 May 2011 10:41:59 +0400
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Subject: Re: limiting pop access to gmail servers ?
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Hi,

> BUT, I suspect there are a LOT of possible IPs that google will use to po=
p
> mail
> > from us ...
>
> You are right about that. According to my pop logs, my servers have
> encounter about 1000 different IPs from google (920 actually).
> Domain names are always like mail-[a-z][a-z][0-9]-[a-z][0-9][0-9]*.
> google.com
> By the way, I'm in europe, I'm not sure USA, Australia or Japan would see
> the same gmail POP clients.
>


You can make active checks for incoming connections. If reverse DNS record
is valid (ip -> resolves to name -> resolves to same ip) and it matches '.*
google.com$' regexp, then it is Google.


--=20
=D0=9E=D0=BB=D0=B5=D0=B3 =D0=9F=D0=B5=D1=82=D1=80=D0=B0=D1=87=D0=B5=D0=B2