Voicemail eMail Notifications stopped working

[dsidata]

Our voicemail email notifications stopped working a couple of months ago. A small percentage of notifications are actually received, but very few with no logical pattern. It could be it happened right after updating to (15.5) SP6. Prior to that is has worked for almost 4 years. Admin notifications are all working.

 

[cobaltit]

So the published SPF record for 3cx.net is this:

v=spf1 ip4:168.245.58.221/32 ip4:151.80.125.122/32 a3.smtp.3cx.net. -all

It seems all of the recent connections seem to be coming from
o3.smtp.3cx.net [168.245.58.221]

You can try making a connector or an IP whitelist from that IP. You may also need want to logging at the firewall level to make sure inbound connections are even being attempted.

 

[dsidata]

I tried with connectors and IP Allow lists but was unsuccessful. That's why I am looking for some documentation about how to configure Exchange 2010 for these messages. Certainly I'm not the only one out there using a pretty vanilla Exchange 2010.
Whitelisting @3cx.net on Symantec should take Symantec Mail Security out of the equation. Also didn't work.
Giving up for today.

 

[cobaltit]

So it's been a while since I messed with Symantec but they had two products that I remember. One was basically a SMTP relay and one was a SMTP sink in the Exchange SMTP connector. If you are using the former and the mail is being rejected by Symantec then the connector would never see it. Also, it's typical for mail filtering products to do RBL checks and such at the initial connection so if it's being refused at that level after the HELO but before sending the mail info white listing based on sender won't work. So you'll want to make sure you are white listing by IP at the very edge of your mail flow.

 

[cobaltit]

Certainly I'm not the only one out there using a pretty vanilla Exchange 2010.

God I hope you are. As an old Exchange guru I haven't installed Exchange in years and I'm thankful for that. I have one client left with an on-prem Exchange server and that's because they are afraid of getting STDs from the 'cloud' but either they will be in the cloud or they will no longer be my client by the end of this year.

Hopefully you'll get it sorted tomorrow with fresh eyes.

 

[dsidata]

New Day, Fresh Eyes.

I called Symantec and they confirmed that what I did took them out of the equation. They walked me through proof that the emails were either not being received or were rejected before their Mail Security kicked in.
Another development was that I tried using another domain address on our same in-house Exchange server. Bingo! The emails worked fine. Problem is, that's an old domain name that's not used any more by my users.
I turned on verbose smtp logging on our server, and tested the multiple email address, all hosted on our exchange server. For the ones that don't work, the messages aren't even hitting our server to be rejected. If they were, I'd see the reject entry in the SmtpReceive log. The ones that work are both logged in the SMTP log and then transport log.

[email protected] no good
[email protected] no good
[email protected] good


So it's looks suspiciously like a 3CX thing. To some email addresses, they aren't even sending out notifications. Go figure that one out!

I think I went above and beyond trying to troubleshoot a 3CX issue...

 

[YiannisH_3CX]

From your description and the troubleshooting you have already done i would recommend contacting our costumer support team so they can check if your domain is blacklisted on our side. You can use this form to do so. State that you are an existing costumer and after providing some details regarding your issue choose the PBX Express (Cloud Instances) category. Our costumer support team will get back to you.