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Emails that never arrive - and no NDRs, no errors, no trace in logs...
I support many different email systems for different clients. The two major ones for us are Exchange/Outlook and Groupwise.
Sometimes our users report that they did not receive emails from a particular sender. When we examine the logs, spam quarantines, etc - in short, everything that we have control over, we never see ANY evidence that an email was sent. And the sender never gets a bounce, or other info to suggest that the email wasn't delivered.
But we know they were. I have experienced it myself - I have several times sent emails to a contractor I use, and he never gets them. I never get an NDR, or even an email reporting delay.
Let me repeat again - when I try to trace these emails, I don't see anything in firewall logs, in email logs, or elsewhere that shows the email entering our network or our system. But I have had users send emails to both me and to the affected systems, and I get get an email, but don't see it enter our clients' system.
Since I don't control their email server, I'm pretty much at the whim of whomever administers their email servers to diagnose the problem. I'm working on one right now where a Verizon.net server fails to send an email to our client, with no NDR, no error, no message, no nothing.
Each time this happens, I have checked the various black-list sites to see if our servers have been black-listed. They aren't, but this should really only affect our ability to send to them. I have in no way that I know of restricted our server from receiving from Verizon.net servers. We do use a MX-redirection spam service for most of these clients, but I have looked in the quarantines and never found our missing inbound email.
So, the question: in addition to trying to get a Verizon.net administrator to investigate the problem, what can I do to figure out the problem?
Sometimes our users report that they did not receive emails from a particular sender. When we examine the logs, spam quarantines, etc - in short, everything that we have control over, we never see ANY evidence that an email was sent. And the sender never gets a bounce, or other info to suggest that the email wasn't delivered.
But we know they were. I have experienced it myself - I have several times sent emails to a contractor I use, and he never gets them. I never get an NDR, or even an email reporting delay.
Let me repeat again - when I try to trace these emails, I don't see anything in firewall logs, in email logs, or elsewhere that shows the email entering our network or our system. But I have had users send emails to both me and to the affected systems, and I get get an email, but don't see it enter our clients' system.
Since I don't control their email server, I'm pretty much at the whim of whomever administers their email servers to diagnose the problem. I'm working on one right now where a Verizon.net server fails to send an email to our client, with no NDR, no error, no message, no nothing.
Each time this happens, I have checked the various black-list sites to see if our servers have been black-listed. They aren't, but this should really only affect our ability to send to them. I have in no way that I know of restricted our server from receiving from Verizon.net servers. We do use a MX-redirection spam service for most of these clients, but I have looked in the quarantines and never found our missing inbound email.
So, the question: in addition to trying to get a Verizon.net administrator to investigate the problem, what can I do to figure out the problem?
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ASKER
Thanks for your suggestions. I had completed most of those diagnostic steps prior to posting. I am partially able to explain some of my symptoms due to configuration settings I discovered after asking the question, and do agree with the general thread that the problem must be with either the MX-redirection spam filter service, or with Verizon for something they're doing that I can't see.
ASKER
Thanks for your many suggestions.
The primary problem is/was a user who was having trouble sending inbound - but I did confuse the issue by adding that I was seeing a similar problem sending to a contractor of mine. I should have kept the question simpler. On the inbound side, I can only look at logs on our firewall and server, and at the spam quarantine (I don't get to look at their logs, but I can start help-desk requests).
I did find a configuration setting that was dropping spam sent to the administrator, but not the end-users. So I now understand why email going to the administrator email account "went away." I still don't understand why his email, sent from verizon.net servers, is classified as spam, although a look into the header does show it accumulated a point toward SFP because it is HTML. I haven't taken the time to see if verizon.net is RBLS-listed, but even if it is, I can't really change that and its up to them to get off the lists and stay off them...
I have white-listed the verizon.net address, and email does seem to be flowing through from this person.
As for my problems sending to my contractor, I haven't spent any time researching that.