Exchange 2010 stopped routing to BT

[Simcfc73]

Over the past few days I have had issues with emails and remote access. Now I am sat here looking at the exchange queue growing with a error "451 4.4.0 Primary target IP address responded with 421 4.2.1 Unable to connect". I was playing with the excghangeconnectivity tool as the staff had reported that their smartphones had stopped connecting to exchange. (mine has been fine). Rebooted it a couple of times but not sure what is the issue.... I have phones Smoothwall just in case there is something array with the routing but they found nothing.. and the 20 minute call to BT was a waste of time. No emails are coming in either which is even worse as last time it did this they all got NDR'd. Think I need to go home and connect from home to check the telnetability of it all. Anyone using BT for their ISP and having issues? or better still anyone know a magic button I can press to get it all back working.

[glennda]

You don't have any smart hosts configured to forward mail onto do you?

 

Or if your using Smoothies anti-spam I guess that is your smarthost but does that forward onto anything?

[Simcfc73]

Yes to smarthost.. its been like that for 2 years and never missed a beat. I don't use any smoothwall spam stuff. The smarthost is set to mail.btconnect.com, I have been on the BT forum and they are changing over to office 365 so I am wondering if they have been toying with settings. Strangley when I run the exchange tools I get errors about connecting to the smarthost on port 25 and it not accepting emails from me... but I can telnet it on port 25.

[Simcfc73]

Actually no routing is going through the firewall now. Sooooooooo. Exchange looks fine (ish), Smoothwall looked fine too according to their techies so that leaves BT. 20 minutes on hold today so not looking forward to tomorrow. I cannot connect to any ports in school (exchange, outlook anywhere, HAP) or even the smoothwall box itself. Tracert to my statics is timing out at the last hop but that could just be cos its blocked.

[twin--turbo]

take the smart host out and use direct delivery instead. see if that works , or try smtp.bt.net

 

also look at email black lists and make sure you no listed ( use mxtoolbox.com )

 

check your MX record from outside.

 

check your Reverse IP is configured correctly, if not get the BT DNS team to create one.

 

we are on BT.NET but don't bother with using their smart host.

 

Rob

[Simcfc73]

Looks like all the port forwarding on my firewall is down too. So I have 2 possibilities

 

The firewall has got all screwed up.

Bt have swapped a cable over somewhere and their routing has been screwed up.

[Simcfc73]

Thanks for the help. restarted the PPPOE connection on the smoothie and it got a different IP address. I think it was a BT problem. Also removed the smarthost and the queue went.

[Simcfc73]

Update: Queue is playing up, some are routing and others aren't.

[glennda]

Update: Queue is playing up, some are routing and others aren't.

 

to me that suggests the issue isn't with exchange.

[Simcfc73]

Nope, got some queues forming with 451 4.4.0 primary target IP unable to connect errors when I just have it using DNS to route. Most emails seem to fly out but some are hanging.

[glennda]

Nope, got some queues forming with 451 4.4.0 primary target IP unable to connect errors when I just have it using DNS to route. Most emails seem to fly out but some are hanging.

 

On the exchange box do an MX lookup for the domains in question (type nslookup at cmd then set q=mx and the domain after). Query both the domains against your local DNS servers (what do these forward to??) and then against googles DNS servers directly 8.8.8.8

[sukh]

Up the logging on the Send Connector to verbose and see what's going on. If using a smarthost confirm with ISP if the allow 25 or 587? Test both.

 

Also, test using Internal DNS lookups, the default. If your internal DNS is working then you shouldn't need external lookups.

[glennda]

 

Also, test using Internal DNS lookups, the default. If your internal DNS is working then you shouldn't need external lookups.

 

My comment was more drawn to make sure they are looking at the same thing - if they are using BT's dns and it has stale records or is up the swanny (which with it being BT is possible).

[Simcfc73]

40 minutes on the phone to BT. The DNS routing was failing on a few sites. When I did the MX lookup it failed too, I didn't use Googles DNS as I got through to BT. They tested the smarthost and its working and lo and behold, it started working on mine too. One thing that I stupidly did was have the wrong address space in the connector on the second connector I had already set up years ago so obviously I was getting an error on the connectors. So fingers crossed, its working again. My biggest worry is the reason it all failed. Now BT are adamant nothing had changed but the fact none of the routing into the school worked including SMTP and RDP suggests to me they have done something and not told me. I do need to sort out my secondary connection so I can do a bit of external testing whilst in school. Because they dynamically assign the router an IP address then just route the static IPs to that there is no was to tell if the assigned one is correct or their routing is.