I am having the same issue. I believe it started a few months ago. Can't seem to find a pattern. Sometime the same e-mail will go through one day but not the next - so its not my SMTP server or the recipient email address. Has anyone solved this yet?
running ColdFusion version 8,0,1,195765
this is an example in the mailsent.log:
"Information","scheduler-5","08/15/12","11:34:44",,"Moved undelivered mail: Mail30590.cfmail to C:\ColdFusion8/Mail/Undelivr directory"
and i have thousands of these in the mail.log
"Error","scheduler-4","08/15/12","11:30:39",,"Exception reading response"
"Error","scheduler-5","08/15/12","11:34:44",,"Exception reading response"
"Error","scheduler-3","08/15/12","11:50:12",,"Exception reading response"
"Error","scheduler-1","08/15/12","11:55:24",,"Exception reading response"
We never found a solution to it, and like you, there's no clear reason and it does appear to be random. We know there is nothing wrong with the email addresses we're sending to.
We can do a small bulk mailing to a few hundred people, including ourselves, and find a small percentage end up in the undelivr folder, we immediately drop them back in the spool and they send fine, sometimes a few don't , repeat the process, and out they all go, rather annoying
This has been happening to us for years so we set up a couple of scheduled jobs to handle it. The first one moves the files from the undeliverable folder to the spool and sends a notification that this has happened. The second runs 15 minutes later and checks the undeliverable folder. If it finds anything, it send notification and then we check to see what happened.
That was one method of taking care of it that did cross my mind. I just needed to be careful that I was not moving genuinly bad emails into the spool and then repeating the process. I could move them and delete what's left a minute later but run the risk of deleting a good email that found it's way in there in-between or one that was moved and bounced back in there again. I could record dates and times but now it's getting messy. Ultimately I would like to fix the problem but it looks like there is no fix for this
Could you upload your 'move' script?
Understood. It's just a pain when there is a constant flow of email going in as the genuine bad email will find its way back into the undelivr folder, but there will also be good ones in there again that need moving.
It's strange how there don't seem to be more complaints about this, I wonder why it does not happen to everybody.
I know this thread is one year old, but in case you didn't find the reason of your problem, here is what I found in my case.
I discovered that my mail server (Mail Enable) has a default limit of 1000 messages sent per hour. So whenever CF has more than 1000 messages to send, it gets blocked by Mail Enable.
I just remove this limit, restarted the SMTP service, tranfered all messages in the spool and POOF!, all messages were gone!
Thanks for taking the time to post in here I never did find a solution, I don't have access to the mail server as we're using the ISP's mail server, even when there is a very low amount of mail going out it still happens, it can literally be on a single email, and nothing has been sent for hours as we're not big emailers (from the server), It may still very well be related to the mail server, although the word 'exception' tends to point me back towards CF, but if you managed to resolve it with a mail server tweak then perhaps it is indeed the mail server. I guess one way would be to try another mail server somewhere, the only problem is that we'd probably suffer from mail delivery issues then as the reverse look ups would not be accurate to the SPF records etc.
I don't have access to the mail server as we're using the ISP's mail server, even when there is a very low amount of mail going out it still happens,
Then you're probably not the only one using the server.
I got a hint from my mail server logs :
"Postoffice Internetique user xxxx has sent too many messages this hour and message rejected."