moderated Re: Unknown bounce issue #bug


Thanks for the info Derek,

I am confused when you say "it is breaking the SMTP connection without sending any message back"

Emails are sent to a recipient without any form of response being required, so unless I have misunderstood what you have said, this makes no sense to me.

As for the possible reasons you have given, very helpful.

The thing is, the script works just fine for all other messages it receives, including messages produced by the same piece of software that the offending 'sender' uses, which in my mind would negate all of those reasons, would it not?

Sorry I have not explained things clearly.

In my group, aircraft logs are posted using a variety of different software.

One of the members of that group is an email address that I have 'attached' a script to. A script, that when it receives any emails, it extracts the data contained and puts it into a database.

No message is automatically sent back, although a sender does have the option to receive one if they so wish. In this case they do not wish it.

I have put some error trapping into my script, by sending myself a copy of the message as soon as it receives it. I receive copies of all messages sent, EXCEPT the one that bounces, which in my mind implies that the message is not being received by my mail server, which makes sense if that message is bouncing.

Hope that clears things up and sorry for the confusion


On 23/05/2021 11:55, Derek Milliner wrote:
First instinct is that the recipient machine running the script is throwing an error and breaking the SMTP connection without sending any message back to the sender; this might explain why the only entry in the 'Reason' is that HTML comment ((<!-- ). Various reasons for this, including:
* Mail handler doesn't have permission to run the script
* Mail handler doesn't have permission to read the script
* Component required to run the script isn't present, is broken or has incorrect permissions/privileges (possibly due to being updated)
* Non-printing character embedded in script, often due to cut & paste between dissimilar OSes (e.g. Windows -> Linux) causing a syntax error
There may be others of course, but without knowing the setup it's speculation right now. I presume from the way you describe the process that you have a script that generates a message which is posted to the group, the message then being delivered to members and processed by the second script. It's highly unlikely to be a problem at the send given that only this one account has the issue.
I would try manually connecting to the recipient's mail server and emulating the delivery process with SMTP commands (EHLO, RCPT TO, MAIL FROM, DATA etc.); this would at least indicate whether it's possible to make a successful delivery (get an SMTP '250' code back). If you have a sample message it can be pasted in after the DATA command to try & generate an expected reply.
If the manual process doesn't work either, then it's a question of the user checking their system & logs to try and nail down the cause of the problem.

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