Question

Locked

port 25 blocked

By johnson_kjohn ·
Dear all,

We are running on Exchange 2000 server.We have around 50 POP3 users.The problem is, some of the ISP has blocked the port 25 instead they have opened the port 587, our POP3 users are not able to send the mails.

1. How to resolve the issue ?
2. As an administrator, whether i have to do some configuration changes on our exchange 2000 server.

Regards,
Johnson

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All Answers

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Could be :)

by Jacky Howe In reply to Sounds more like a homewo ...

anyway the article explains most of it.

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Good article in reply to a really crap question ...

by OldER Mycroft In reply to Could be :)

I've been waiting since last night (local time) for someone to voice MY confusion!

This has now come to pass.

Sorry - what is the question???

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It was here somewhere :)

by Jacky Howe In reply to Good article in reply to ...

hang on i'll do a search.
What am I looking for.

< emoticons playing up >

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I'm not sure ...

by Churdoo In reply to port 25 blocked

... what all the confusion is about.

The users are accessing their Exchange 2000 email from home via POP3. To send outbound, these home users are trying to SMTP from their home email client through their home ISP to the Exchange 2000 server at the company site. Herein lies the problem as most ISP's nowadays restrict SMTP communications to the ISP's own resources, and so a direct port 25 SMTP connection to the company Exchange 2000 server is disallowed.

The options are:
a) Have the home users use their own ISP resources for their outbound SMTP (this outbound email can still send as their company exchange 2000 email address)
b) have the home users configure their outbound SMTP to a different port (and of course reconfigure the company server/firewall accordingly)
c) retrain the home users to utilize Outlook Web Access (OWA) versus the home POP/SMTP email clients.

Options a and b are support nightmares for several reasons.
Option a --
1) you need to rely on home users to perform technical steps in configuring their SMTP client;
2) you need to be able to support each of your users' ISP policies;
3) you need to support X number of client software (or restrict users to 1-2 common clients that you will support)
4) You have no way to monitor or control the users' outbound communications
Option b --
5) you need to rely on home users to perform technical steps in configuring their SMTP client;
6) you need to support X number of client software (or restrict users to 1-2 common clients that you will support)
7) Server reconfiguration is required for the alternate SMTP port
Some ISP may at any time recognize SMTP traffic on the alternate port and may block at any time without warning;

Option C is the easiest option to support, and with OWA's features even in exchange 2000, the user interface is very good too. The most obvious diadvantage is the initial culture shock of the users' utilizing the browser interface instead of the POP3/SMTP client.

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Okay, I think I follow now.

by Dumphrey In reply to port 25 blocked

1) Client outgoing on 587/smtp
2) Client incoming on 110 same as always.
3) Modify smtp virtual server to use port 587 instead of 25 (quick n dirty) OR translate 587 external to 25 internal at the firewall (better idea).

This should have you up and going. Make sure to tighten down access controls etc.

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