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exchangeserver2k behind dialup adsl modem/sending message question

Posted on 2002-05-17
Medium Priority
Last Modified: 2010-03-05
I got an exchangeserver2k behind dialup adsl modem which get dynamiclly assigned IP each time it dials up.

Question 1 :

without an ISP provided smtp server as smarthost, can I use the dynamiclly assigned IP as an smtp server to send/expand email. If not, then what is the big mistery and are there any documentation on the web explaining it?

Thank you very much.

Question by:wuzhongdl
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Accepted Solution

Zak_McKracken earned 480 total points
ID: 7018261
Yes you can use it to *SEND* email, but you won't be able to recieve email unless you've got a MX record pointing to the updated IP address you get.

There are some servers ( etc) that will allow you to do this.

You may have issues if you are talking to tightly secured mailservers, as mail can be rejected from a host if the reverse lookup doesn't match the IP address/hostname that you supply.  (eg: "i am 'mailserver.myhost.domain.ext' and my IP address is", the server that you are 'talking to' checks the hostname on IP and gets 'cablemodem.location.isp.ext', and then kills the connection.

Author Comment

ID: 7018292

I will give it another try tomorrow. I know the implecation of MX and receiving. what am concerned is just sending. I know MS beafed up smtp on IIS5 after installing exchange. but not too much.
then why it is not possible,(when there is no exchange server, just IIS) to put the dynamiclly assigned IP as the smtp server in the Outlook Express configuration to let it send email?

also, if I remembered right, in the configuration I explained, the letter would stay in the smtp queue. I use hotmail and yahoo as the test email receipient. do you think they are performing reverse DNS lookup?

Expert Comment

ID: 7019193
I don't believe that they would fail (they certainly don't for me (just a smtp server, not exchange - but that shouldn't matter).  You might want to try telneting out on port 25 to those mail servers and 'emulate' sending a mail.  If you don't know how to do that, do a google search on "send mail via telnet" and you should find instructions on how to do it.
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Author Comment

ID: 7019240
Thanks for your reply

But if anyone can use their own dynamiclly assigned IP as the smtp server then, why would below soft
exist? there are other soft like that but not too many.
Also. you certainlly can not take your dynamic IP( after dialup ) as the smtp server in your outlook
I have read the help file but find not much help. I think it is the same question/problem I asked first.
Direct Mail 1.0  

From the developer: "Direct Mail is a powerful Bulk Mailing tool which sends a large number of e-mail
directly recipient's mail server without using your ISP's SMTP server. It effectively turns Desktop
Computer to a SMTP server. Since it mails directly using DNS, recipients get your message several times
faster than using conventional e-mail systems. Whether its advertising your business or to send product
updates, newsletters, and other materials to many recipients Direct Mail gets the job done."

Expert Comment

ID: 7019702
You're comparing apples with motor bikes here - the bulk mailing software is one application sending the same email to multiple email addresses.

Software like that is simply to quickly generate large volumes of mail, bypassing your ISP (a "good" thing for spammers, as they're not being tracked by their ISP, and making it harder for spam tracking.

As for setting your smtp server in OE, you'd point it to the fixed internal IP address that you are using.  If you've got multiple IP addresses, and your all of your computers are running on real world IP's, then you *will* have a problem with doing this, unless you set your smtp server to the same dynamic IP address that you setup the MX record for.

To setup a mail server, you either have to have a fixed IP address (either a 'NAT' address, or a hostname that is updated when you change your IP address, or have a fixed IP address.

If you don't have a way of tracking it so that you can resolve it somehow, you're not going to be able to locate the host, so you won't be able to send email.

Please provide details if this doesn't answer your question.

Expert Comment

ID: 7019778
to use exchange server to send and recieve mail at home use

dns2go. i have a dynamic ip address at home with exchange 2000 and i never need to do any reconfiguration. no mx record needed. the dynamic dns software directs all traffic http,smtp,ftp etc to my ip address and my firewall sendsthe packet to the appopriate machine.

Author Comment

ID: 7020619
Thanks for all the reply

Let's make it simple. Just take one laptop(with 2kserver) one OE and one dialup modem. And I don't concern receiving mail. just sending email.

You dial up first, then you want configure OE to send email. what would you put in the OE SMTP configuration? can it be the current dynamically assigned IP?

Author Comment

ID: 7020672
I think the reverse lookup is the main problem I have. I can send to some other email address now, but not to my own main yahoo account which I used to test connectivity. guess that is the reverse lookup thing blocking it.

Thanks for the help.

Expert Comment

ID: 7021293
Ok, glad to help :)

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