Strange problem with Mail Spool with CF9
We recently moved our site at work from CF7 to CF9 and I'm noticing a strange behavior when sending out bulk emails. If I send 500 emails at once they all quickly end up in the spool, but then they are actually leaving the spool for the mail server one at a time every one or two seconds. This is much different behavior than how the process was working on CF7. I have the Spool threshold set to 20 seconds on both the old and new servers but no matter what spool interval I set on the new CF9 server, it is processing one email at a time out of the spool.
I have made sure that my antivirus, Symantec Endpoint Protection, is not monitoring the spool directory as this caused performance issues in the past. I verified that my mail server is not currently backed up or overwhelmed. One difference is that on my CF7 server the smtp server that I was using to send mail was on the same server but with the CF9 setup I'm on a different box but still using the same old mail server located on the previous server. I don't see why this would cause such a severe drop in performance. Is there a giant drop in performance when not using a local smtp server with cfmail?
In my example above, I mention sending out 500 emails but in reality I need to send around 40,000. With the emails leaving the spool at such a slow rate it will take several days to send the email which will not work out. In the past, on CF7, I was able to get the 40,000 emails out in around 8 hours. I do not send them all at once, but in 500 email chunks. I do this by monitoring the spool directory with cfdirectory and only sending the next chunk of messages when the number of files in the directory gets below 50. This allows all of the emails generated by the website to be placed in the queue without having to wait for the entire bulk email to be sent, which keeps the emails from being delayed for hours.
If anyone has any insight as to why I'm having these issues with email moving so slowly at of the spool I'm all ears. I have spent the day searching for an answer and so far have not found anything that could be causing the issue. Hoping some other CF bloggers out there might have some ideas as to why I'm seeing this strange behavior.
That is odd. Are you sending messages to a 3rd party SMTP server or using SMTP services built into IIS?