Based on my finding, yes it is. I already started noticing this issue starting last year December when my users starting to complain about their email messages not reaching several existing contacts. Slowly things get even uglier between February and March, the messages would deliver into junk in Outlook automatically. The 3rd party email like Gmail services follow, sending them into SPAM folder. Even the Barracuda Spam Firewall sees as threat and start rejecting.
As far I know, my company experiences the worst when the email messages almost completely go AWOL in 3rd week last month. The 4th week, the messages all stuck in the queue for unknown reason and getting relay messages. We found out the local domain name suddenly no longer working and tried using smtp.brunet.bn as temporary solution. It didn’t work either. In the end, we had to convince the management to purchase 3rd party SMTP service to get the whole thing running.
It’s not like we did not investigate the physical server, Microsoft Exchange and check for possible domain name being blacklisted. But if our local domain names are found healthy in numbers known global blacklisted database and the spam firewall had no technical issue. So what did we miss here then? I thought could be one of the users infected by virus. Still didn’t find any infected PC in the office and high rate spam activities report by Barracuda. I decided to turn to MX Toolbox to find out.
MX Toolbox has numbers good range of useful tools to test your exchange for any issue in the configurations especially newly deployed server. Their new Email Deliverability tool is one of them. It basically allows you to send a test message into their systems to analyze the blacklist reputation of your outbound IP address. This way, I am able to know whether the domain name has problem after the messages goes out from the SPAM firewall. The results return and reveal the truth. The outbound address actually is non-other manage by one of the Brunet SMTP server. Ta-da!
That’s not all, the current outbound IP address was reported blacklisted. I verify the Brunet SMTP IP address I know of through different known blacklist check website were indeed listed. This clearly explains a lot why the email messages would flag as SPAM and never reached to the clients. The question is, do the Brunet teams know about this? I don’t know. One of them doesn’t seem to interest listened when I made a phone call yesterday report what I find. Politely sound denial there are any issue with Brunet SMTP and keep insisting that our domain is blacklisted (which is not). In the end I was told to send the report with test screenshots by email messages so they will look into it. I did and hope they will investigate.
The facts here are the problem above is not new. I can say this time we faced are quite serious. I still remember someone who worked in Brunet support predicted this few years ago and warned us not to used either own domain name or smtp.brunet.bn as outbound in the exchange. He is right on this. My boss also never listen to the advice and ours to stop hosting new clients email at Brunet server grain of salt for so many years. Hopefully this time a good wake up call.