We are having heavy problems with our installation of phpList.
It tends to send out a large amount of emails, but when it comes to an email address which does not exist, it kind of hangs up and keeps circling through all wrong email addresses trying to send thousands of times.
In the log it says “Could not instantiate mail function”, when running on php mailer, or “mailbox unavailable invalid DNS MX or A/AAAA resource record”, when running on SMTP. For some reason this is not handled by bounce management, but blocking the system. Now, it is sending with 1 mail every 80 seconds (and going slower) instead of 3,500 every hour, which would be normal.
I would be happy, if anyone could give me an idea, where this is coming from.