I'm having a small issue with sending email on my Exchange 2010 Server. If I send email with Outlook and OWA, it works no problem, the issue is with Thunderbird, but I imagine I have my connectors configured incorrectly. I can receive email with no problems.

I have my hub transport server setup on a different VLAN and if I setup a mail client on that VLAN I can send mail no problem. If I am on a different VLAN, the SMTP ports are not visible for some reason. Its not a firewall issue, I checked. Any ideas?

  • Is this POP, IMAP or does Thunderbird have some sort of Exchange plugin? – Ben Pilbrow Feb 23 '11 at 13:43

How did you check that there is firewall issue? If it is not firewall issue, may be it is the hub between the VLANs issue? Can you connect to the SMTP port using TELNET?

c:\> telnet <ip-address> <smtp-port>

Such as:

c:\> telnet 25

Port 25 is the default SMTP port.

  • I tried that test, and it works on a computer that is on the same VLAN as the Exchange server. It also isn't working externally, which is an issue. Services like IMAP and POP are going through fine on all subnets. – user49349 Feb 23 '11 at 14:01
  • Then I guess it is a firewall problem! You should check why external network denied access to the SMTP port. May be the system administrator of the network highly protect the SMTP port because it can be used as relay (for spamming or injecting unsolicited emails) so that they protect the SMTP port more. – Daniel Baktiar Feb 24 '11 at 8:38

Can you explain a bit about your Exchange architecture, e.g. do you have a Client Access Server as well?

You should check the Windows firewall on the server. But what you will need is a receive connector set up to listen on the subnet that your clients are trying to send from. I suspect it's more likely to be a IP problem than a VLAN problem.

Open Exchange management Shell and type Get-ReceiveConnector <connector name> | fl for the receive connector you have created to handle this, and post the results here. That will help.

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