Re: How to auto detect a remote IMAP/POP3 server given only an email address ?

mp- wrote:
On Dec 28, 5:56 pm, Iván Sánchez Ortega <ivansanchez-...@rroba-
escomposlinux.-.punto.-.org> wrote:
The Natural Philosopher wrote:
take the domain part of their address and try looking for MX, then A
records..and hope their ISP doesn't have a relay in the way..
... And do a port scan on pop3.domain, and imap.domain, and do keep a
whitelist of known domains and servers (together with a manual way of
adding a domain+server to that whitelist).

--
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Iván Sánchez Ortega -ivansanchez-algarroba-escomposlinux-punto-org-

Why was God able to create the universe in only seven days? Because he
didn't have an installed base to deal with.



Doing a port scan on imap.domain.com, pop.domain.com, etc.. just seems
like taking an educated guess as to what the IMAP/POP3 server name
is.

Does a DNS record exist describing the hostname for a particular
domains IMAP/POP3 servers? It seems that the MX record is only for
SMTP - which doesn't necessarily mean IMAP/POP3 is on that same
machine.


No DNS record for IMAP/POP3 because it isn't used for mail transfer. SMTP needs it so that one system can send to another system. But with IMAP/POP3 the user is requesting mail. Entirely different process which doesn't require special DNS records.

As others have said - try the MX record for the domain. If that doesn't exist, try the A record. If that doesn't work, you're SOL.

And it will fail on a large number of systems. Many large ISP's and some large hosting companies use different IMAP/POP3 servers to keep the load down on a single server, for instance. And many large companies do similar, also.

--
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Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
jstucklex@xxxxxxxxxxxxx
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