ISPConfig mail server fix

I have ISPConfig installed. It works very well for the most part.

I have had email issues fior ahile. Nothing major, but it does hiccup a bit.

1 - the mail server does not always accept connections form outside the local network. Very inconvenient.
2 - Issues with sending emails getting blocked and labelled spam. I can provide more details.

3. Ispconfig has a known bug where Mailman does not create a new mailing list correctly. I'd like this fixed.

I am looking for someone to look at these issues and if possible suggest other improvements to improve my mail server.

Thanks

Joseph