Re: testing email deliverability... [message #186038 is a reply to message #186037] |
Thu, 05 June 2014 01:40 |
Keith Keller
Messages: 5 Registered: June 2014
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["Followup-To:" header set to comp.os.linux.misc.]
On 2014-06-05, The Natural Philosopher <tnp(at)invalid(dot)invalid> wrote:
>
> I want to make sure that anyone using them has a valid reply address set
> in a web form BEFORE I forward the message on to the site administrators.
There is absolutely no way to do this for arbitrary domains. Some
MXs will accept all mail addressed to it, then decide later how to
handle the message (discard, bounce, deliver).
> that will return true or false if gmail accepts the user as known (yes
> the spam is always @gmail.com) WITHOUT having to write a dns mx lookup,
> then connect to socket 25 and etc etc etc..
It's not even possible (for an arbitrary domain) *with* doing an MX
lookup and connecting to port 25. It will be possible for some MXs but
not all, and there's no way of determining ahead of time whether a
domain will do this for you or not. This is why many sites require
separate confirmation by sending email to the target with a link that
verifies that the recipient actually received the mail.
--keith
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