Is phplists the best self hosted autoresponder?

Hello,

I am looking for the most reliable autoresponder mail script (ideally in php) that I can install in my server (self hosted) and tweak to my won needs. For me it is important that the autoresponder service can manage a ver large list and amount of emails.

I arrived to the forum reading this thread, and that is exactly the kind of information I was looking for... but with the slight twist above (that has to be really scalable and customizable). This is why I opened a new thread.

I am building an application that will allow users to build their own site in my platform. It will be a site designed to capture leads, so it is very important that they have available an autoresponder to keep the relationship with these leads. I know I could build intengration with the main email autoresponders (aweber, etc), and I will do that... but i wanted to also offer my own email platform within the package (since a lot of the things that would go on the emails would be specifically the content that the site generates), so it seems that a custom solution that can automatically send these emails from within the application would be the best solution because it would integrate best. I would be using this application with Amazon SES or Sendgrid for high deliverability.

I have seen php list, which seems to be a great alternative... open source, php & customizable. However not long ago, a developer with expereince with phplists told me that Phplists is meant more for smaller email lists & does not work well for very large lists. He explained that there was a better alternative for that. He gave me the name but i cannot recall it. Do you agree with the above? I mean... do you agree that phplists does not work well for large email lists & many emails? Is there a better alternative? My site is in php, this is why I was looking for the autorespoder in php for best integration. Any comments or suggestions form your side would be highly appreciated.

Thanks!