Port 25 NOT blocked but still can't receive e-mail

[djm583]

Hi,

I'm connecting to a remote server (VPN) and trying to set up pre-existing e-mail accounts there.

Using exactly the same information (there are no typos!) I've tried to view the account in Outlook. However, the account can only send test e-mails, not receive them. However, receiving/sending e-mails via a desktop (i.e. NOT conencted to the remote server) is successful.

I've rung up both the VPN provider and the domain holder (BT) but they can't help.

Additionally port 25 is NOT blocked.

Any help/suggestions would be greatly appreciated!

David.

 

[jet042]

Port 25 is for SMTP (sending of mail) only. If you are using POP3 to retrieve mail that goes over port 110. IMAP uses port 143.

 

[djm583]

Sorry, I should have stated that we are indeed using pop as the incoming mail server. Additionally ports 110 and 143 are also open; I've checked all standard comm ports.

 

[smah]

I'm trying to make sure that I understand the conditions correctly:

[ul][li]At the client pc, you can send & recieve via this mail server when not connected to the VPN[/li]
[li]At the client pc, you can only send via this mail server when connected to the VPN[/li]
[li]The mail server in question, is inside the network to which you make the VPN connection.[/li][/ul]

If this is correct, in order to have these condtions, the mail server must also be directly available to the public internet. So my first question is: Is it only available by public internet and not from your local network? This problem ultimately lies in one of 4 things:[ol][li]Gateway that the client is using[/li]
[li]Routing of client traffic[/li]
[li]Name Resolution on the client. Which is almost the same as #1, but not quite.[/li]
[li]Firewall or access restrictions on the mail server. This is the most likely in my opinion.[/li][/ol]

 

[djm583]

smah: I'm really not an expert with e-mail or computers in all honesty, but I'll try to answer as best I can.

To clarify (more for me than for you) The VPN is a remote server which we can access remotely to create literally a link to a server in Manchester. We can send/receive e-mail on any computer APART from via the VPN, through which we can ONLY send mail, NOT receive.

We do not have a local network as such.

As to your four problem areas, I'm reasonably sure it's not a firewall, since I rang up the hosts of the server and asked them the very same question.

However, to answer your query of 1, 2 and 3 you may have to clarify for me.

 

[djm583]

* but per condition three yes, the mail server (Outlook) is inside the VPN server.

 

[noveyron]

What are you using for a VPN Client?

Do a Google on your client + split dns

 

[58sniper]

the mail server (Outlook)

Outlook isn't an email server. It's the client.

Something to keep in mind here is that the ports listed above are the default unsecured ports. POP3 uses 110 to download mail, and SMTP uses 25 to send it. However, secured POP3 uses 995, secured IMAP4 uses 993, secure SMTP uses 465.

Additionally, authentication may be required on the server for POP3 clients to retrieve mail.

Pat Richard MVP
Plan for performance, and capacity takes care of itself. Plan for capacity, and suffer poor performance.

http://www.ucblogs.net/blogs/exchange/

 

[SimonDavies]

One thing to also consider, when you connect to the VPN you probably won't be connecting on the same IP address range, has your routing table for the corporate lan also got routes to the VPN network because if they haven't you're simply not going to receive anything from that network.

Another question for you, when you're sending out are you sending out via a public SMTP gateway or via you're own internal gateway, if it's an external gateway that again could point to an addressing issue.

When you're connected to the VPN are you still able to browse the internet, are you able to browse the internal network?

I think that for me the first port of call would be to make sure that your internal networking tables are set up correctly, secondly I would check to see what smtp gateway I am sending thru (try to telnet onto your smtp gateway to see if you can get onto it, remember that you have to specify the port when you telnet onto it because telnet uses 23 by default where as you want to connect on 25 for the gateway).

SimonD.

The real world is not about exam scores, it's about ability.