Need help with mailing and proxies

Hello, I own a linux vps with port 25 closed. I want to install a mailserver on that linux vps which uses a proxy IP for sending outgoing emails. Now i have proxies that have port 25 open now I only need a way for a linux server to connect through those proxies to send outgoing emails.
and the proxies are backconnect supported so i connect through a static hostname and get a different IP which i also have the option to have it stick to a static IP and only change whenever an API call is...

Need help with mailing and proxies

by sulz47 via TBN