Sorry about the delay I've been having serious server troubles I've had to work on around the clock. As you know forum support is completely free and unlimited, so expect delays occasionally when we are busy.
Welcome and confirmation messages use the PHP mail() function to send email, while list email uses SMTP.
There are a number of reasons your emails aren't going out, most of which are already mentioned in this forum. 1) something could have changed with the PHP configuration. 2) you could have hit a hosting limit on the amount of email you can send over a period of time.
I recommend that you test the PHP mail() function by changing your mailing method to it from SMTP and sending a test email to a test list containing a few of your addresses on various providers.
Do you have the same problem sending with SMTP, or are those messages going through?
