Exchange 2010 SP3

[Jawloms]

Got a problem where my site won't email @suffolk.gov.uk addresses. All other emails go. Looking in the Queue Viewer I can see 9 emails sitting there with the queue saying;

 

451 4.4.0 Primary target IP address responded with: "554 esa3.hc742-68.c3s2.iphmx.com." Attempted failover to alternate host, but that did not succeed. Either there are no alternate hosts, or delivery failed to all alternate hosts.

 

If I right click and do "Retry" then it has a bit of a think and then says the same. When I first started looking in to this problem half an hour ago, nslookup to suffolk.gov.uk failed on the exchange server, but worked on all the other servers I tried it on. An ipconfig /flushdns on the exchange solved that, but the emails still aren't going. nslookup to all other addresses I tried worked. PING resolves to the correct IP, and did even before the /flushdns.

 

Where do I go next please? We kinda need to be able to email the LA!

 

Thank you

 

Stuart

[3s-gtech]

The error suggests either DNS as you've found, or your firewall (or theirs) is blocking the connection. What CU are you on? Can you check with them to make sure they're accepting mail from you? I had to do this recently with a public authority, and it was due to dodgy internal mail routing so I was advised to change to 8.8.8.8.

[Jawloms]

I'm on "Update Rollup 21 for Exchange Server 2010 SP3 May 7, 2018 14.03.0399.002"

 

I've spoken to someone there and they are receiving other external email. Seems odd they appear to be the only domain I can't send to.

[Jawloms]

They'd blacklisted me

 

Now resolved.

[3s-gtech]

Thought that was a possible! Got to love LAs!

[Jawloms]

Along these lines, I have a lot of junk in when I look at Queue Viewer. I suspect it's loads of NDRs trying to go off to email addresses which are SPAMming me, which I think is why I get on the occassional blacklist. Do you lot send external NDRs? If not, how do you get round it?