Unfortunately, this problem extends outside of 1-2-All. 1-2-All is a PHP script, and as such, it can only do what PHP allows it to do. PHP is the one handling things "under the hood". So, when 1-2-All starts sending, it is calling a mail() function (native PHP function, http://www.php.net/mail ). If that function returns TRUE, 1-2-All logs "sent", otherwise "error".
However, what happens beyond that point is out of our hands. What PHP does is it calls your server's mail transfer agent (mta) which actually handles the email sending from your server. If the email (for some reason), doesn't leave the server, or does not reach the destination, there is no way of knowing that, in any PHP script.
What you would have to do is contact your server admin and ask him to look into MTA logs. He might find out what happened to those emails. If the server rejected the message due to bad formatting (which would mean the message preparation phase is flawed), then contact support so someone can look into what your server admin reported as a problem.
If you are using one list, and setup two different filters, then all settings are used in both cases in the same way; only the subscriber list is different. If the first one went out properly, then the second one wouldn't only if your mail server (mta) rejects it due to a limit, or some other problem that can arise (insufficient memory / file space, etc...)
If you are an external SMTP server you should check the MTA on that server.
