Hi Dan,
Thanks for your email!
I read about the meaning of “Could not instantiate mail function”, but this can not be the reason. Because the system sends out 10,000 email before starting to make problems.
I can blacklist this address, but it’s some 350 email addresses, and I can’t blacklist all of them. I thought, phpList would blacklist bounced emails automatically? And isn’t this kind of error kind of a bounce? I’m puzzled…