I have been working on a test server with a /29 and it had been working smoothly with 2 domains.

I then moved the server onto a new set of IP Range being a /28 holding all configs the same.

However since changing the IP on the Hyper-V Host to the new range - Exchange 2013 has stopped sending emails out and throwing the following error:

EXCH1.test.local rejected your message to the following email addresses:
z***r@gmail.com (z***r@gmail.com)
EXCH1.test.local gave this error:
Unable to relay 

Your message wasn't delivered due to a permission or security issue. It may have been rejected by a moderator, the address may only accept email from certain senders, or another restriction may be preventing delivery.

Diagnostic information for administrators:
Generating server: EXCH1.test.local
z***r@gmail.com
EXCH1.test.local
Remote Server returned '550 5.7.1 Unable to relay'

NOTE: I have not changed anything apart from the PUBLIC IP. Internal IP is 192.168.18.20 and this had not changed. Receiving emails from anywhere is not a problem. Server is single multi-role server.

Here is the Transport Agents:

[PS] C:\Windows\system32>Get-TransportAgent

Identity                                           Enabled         Priority
--------                                           -------         --------
Transport Rule Agent                               True            1
Malware Agent                                      False           2
Text Messaging Routing Agent                       True            3
Text Messaging Delivery Agent                      True            4

Here is the Receive Connectors:

[PS] C:\Windows\system32>Get-ReceiveConnector

Identity                                Bindings                                Enabled
--------                                --------                                -------
EXCH1\Client Proxy EXCH1       		{[::]:465, 0.0.0.0:465}                 True
EXCH1\Outbound Proxy Frontend EXCH1 	{[::]:717, 0.0.0.0:717}                 True
EXCH1\Client Frontend EXCH1     	{[::]:587, 0.0.0.0:587}                 True
EXCH1\Default Frontend EXCH1    	{0.0.0.0:25}                            True
EXCH1\Default EXCH1             	{0.0.0.0:2525}                          True

Default Frontend - not changed (TLS, mutTLS, Basic, BasicTLS, Integrated, ExServer - ExchSvr,LegExchSvr, Anon) - scoped * port 25

Default - not changed (same as above, but ExchUsers instead of Anon) - scope 192.168.18.0/24 port 2525

I am sure this is so simple, however I cannot get my head around why it is rejecting outbound emails to any domain outside the org.

I have tried creating a new Receive Connector pure for Anon for internal exchange server however resulted in the same even with the following command:

[PS] C:\Windows\system32>Get-ReceiveConnector "Outbound Relay for Internal" | Add-ADPermission -User 'NT AUTHORITY\Anony
mous Logon' -ExtendedRights MS-Exch-SMTP-Accept-Any-Recipient

Here is the Send Connector for reference and sends via MX directly:

[PS] C:\Windows\system32>Get-SendConnector

Identity                                AddressSpaces                           Enabled
--------                                -------------                           -------
Send Connector                          {SMTP:*;1}                              True

I have tried deleting the Send Connector and the latter 2x Receive Connectors without any change. Have restarted the server and Transport Service after making changes.

Any help would be greatly appreciated.

 One thing that is strange is that I cannot telnet to any SMTP outside as it is always being accepted by EXCH1 constantly - not sure if this has anything to do with it!

• Edited by InexperiencedPorkRoll 16 hours 3 minutes ago

If EXCH1.test.local is your Exchange server, then what you're showing is not a test that the server will send outbound mail, but that it accepts mail for a recipient outside your organization, which is what relaying means.

The new receive connector must have criteria selected on it that make the client you're sending from use it.  Usually that's the RemoteIPRanges property, where you enter the IP addresses of the hosts that are allowed to relay.

Sorry I may not understand your reply, however my interpretation of your comment is that I am trying to send other domains through this exchange server. If so, my reply would be:

Currently the server is hosting 2 test domains and the MX are pointed to this server. It will receive emails not a problem, however when sending out emails as any domain, it throws the error.

Can you/someone please explain which connectors are used when sending emails from OWA?